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Nie Z, Nambu N, Marsh KA, Matteo D, Patel CK, Zhang C, Wu Y, Carlström S, Morales F, Patchkovskii S, Smirnova O, Ivanov M, Joshi C. Bidirectional Cascaded Superfluorescent Lasing in Air Enabled by Resonant Third Harmonic Photon Exchange from Nitrogen to Argon. PHYSICAL REVIEW LETTERS 2024; 133:063201. [PMID: 39178428 DOI: 10.1103/physrevlett.133.063201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 06/18/2024] [Indexed: 08/25/2024]
Abstract
Cavity-free lasing in atmospheric air has stimulated intense research toward a fundamental understanding of underlying physical mechanisms. In this Letter, we identify a new mechanism-a third-harmonic photon mediated resonant energy transfer pathway leading to population inversion in argon via an initial three-photon excitation of nitrogen molecules irradiated by intense 261 nm pulses-that enables bidirectional two-color cascaded lasing in atmospheric air. By making pump-probe measurements, we conclusively show that such cascaded lasing results from superfluorescence rather than amplified spontaneous emission. Such cascaded lasing with the capability of producing bidirectional multicolor coherent pulses opens additional possibilities for remote sensing applications.
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2
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Qin S, Zhou C, Mei H, Lu Q, Wang K, Jiang Z, Liu X, Peng P, Xu L, Liu Y. Comparative study of the multiple wavelength lasing of nitrogen ions: the role of vibrational level-dependent photoionization. OPTICS LETTERS 2024; 49:2421-2424. [PMID: 38691734 DOI: 10.1364/ol.517496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 03/09/2024] [Indexed: 05/03/2024]
Abstract
We report on an optical amplification and energy threshold of the two most prominent emission lines, 391.4 and 427.8 nm, of the cavity-less lasing of nitrogen ions pumped by femtosecond laser pulses. It was found that the two transitions both show optical amplification under a low gas pressure condition, while the 391.4 nm emission is barely amplified under high gas pressure. Moreover, the 427.8 nm emission presents a significant lower pump laser energy threshold and a larger gain factor than the 391.4 nm emission. Numerical simulations based on a three-state coupling model suggest that the smaller ionization Franck-Condon factor from the ground state of N2 to the vibrational level ν = 1 in X 2 Σ g+ state of N2 + favors the formation of population inversion corresponding to the 427.8 nm emission. Meanwhile, the competition between the strong field ionization and excitation induced by the pumping laser requires higher laser intensity to acquire the population inversion for the 391.4 nm radiation, leading to a corresponding larger energy threshold.
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3
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Gao J, Zhang X, Wang Y, Dong J, Lei M, Liu Y, Wu C, Gong Q, Jiang H. Controlling the Polarization of Nitrogen Ion Lasing. J Phys Chem Lett 2024; 15:3805-3811. [PMID: 38557052 DOI: 10.1021/acs.jpclett.4c00004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Air lasing provides a promising technique to remotely produce coherent radiation in the atmosphere and has attracted continuous attention. However, the polarization properties of N2+ lasing with seeding have not been understood since it was discovered 10 years ago, in which the polarization behaviors appear disordered and confusing. Here, we performed an experimental and theoretical investigation of the polarization properties of N2+ lasing and successfully revealed its underlying physical mechanism. We found that the optical gain is anisotropic, owing to the permanent alignment of N2+ induced by the preferential ionization of the pump light. As a result, the polarization of the N2+ lasing tends to align with that of the pump light after amplification, which becomes more pronounced as the amplification factor increases. Based on the permanent alignment of N2+, we built a theoretical model that analytically interpreted and numerically reproduced the experimental observations, which points out the key factors for controlling the polarization of N2+ lasing.
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Affiliation(s)
- Jingsong Gao
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Xiang Zhang
- Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Yang Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Jiahao Dong
- Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Mingwei Lei
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Yi Liu
- Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
- CAS Center for Excellence in Ultra-intense Laser Science, Shanghai 201800, China
| | - Chengyin Wu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Qihuang Gong
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Hongbing Jiang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
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4
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Garriga Francis KJ, Zhang XC. Local measurement of terahertz field-induced second harmonic generation in plasma filaments. FRONTIERS OF OPTOELECTRONICS 2023; 16:44. [PMID: 38091154 PMCID: PMC10719236 DOI: 10.1007/s12200-023-00095-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 10/29/2023] [Indexed: 12/17/2023]
Abstract
The concept of Terahertz Field-Induced Second Harmonic (TFISH) Generation is revisited to introduce a single-shot detection scheme based on third order nonlinearities. Focused specifically on the further development of THz plasma-based sources, we begin our research by reimagining the TFISH system to serve as a direct plasma diagnostic. In this work, an optical probe beam is used to mix directly with the strong ponderomotive current associated with laser-induced ionization. A four-wave mixing (FWM) process then generates a strong second-harmonic optical wave because of the mixing of the probe beam with the nonlinear current components oscillating at THz frequencies. The observed conversion efficiency is high enough that for the first time, the TFISH signal appears visible to the human eye. We perform spectral, spatial, and temporal analysis on the detected second-harmonic frequency and show its direct relationship to the nonlinear current. Further, a method to detect incoherent and coherent THz inside plasma filaments is devised using spatio-temporal couplings. The single-shot detection configurations are theoretically described using a combination of expanded FWM models with Kostenbauder and Gaussian Q-matrices. We show that the retrieved temporal traces for THz radiation from single- and two-color laser-induced air-plasma sources match theoretical descriptions very well. High temporal resolution is shown with a detection bandwidth limited only by the spatial extent of the probe laser beam. Large detection bandwidth and temporal characterization is shown for THz radiation confined to under-dense plasma filaments induced by < 100 fs lasers below the relativistic intensity limit.
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Affiliation(s)
| | - Xi-Cheng Zhang
- The Institute of Optics, University of Rochester, Rochester, NY, 14627, USA.
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5
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Mei H, Gao J, Wang K, Dong J, Gong Q, Wu C, Liu Y, Jiang H, Liu Y. Amplification of light pulses with orbital angular momentum (OAM) in nitrogen ions lasing. OPTICS EXPRESS 2023; 31:31912-31921. [PMID: 37859005 DOI: 10.1364/oe.500041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 08/23/2023] [Indexed: 10/21/2023]
Abstract
Nitrogen ions pumped by intense femtosecond laser pulses give rise to optical amplification in the ultraviolet range. Here, we demonstrated that a seed light pulse carrying orbital angular momentum (OAM) can be significantly amplified in nitrogen plasma excited by a Gaussian femtosecond laser pulse. With the topological charge of ℓ = ±1, we observed an energy amplification of the seed light pulse by two orders of magnitude, while the amplified pulse carries the same OAM as the incident seed pulse. Moreover, we show that a spatial misalignment of the plasma amplifier with the OAM seed beam leads to an amplified emission of Gaussian mode without OAM, due to the special spatial profile of the OAM seed pulse that presents a donut-shaped intensity distribution. Utilizing this misalignment, we can implement an optical switch that toggles the output signal between Gaussian mode and OAM mode. This work not only certifies the phase transfer from the seed light to the amplified signal, but also highlights the important role of spatial overlap of the donut-shaped seed beam with the gain region of the nitrogen plasma for the achievement of OAM beam amplification.
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6
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Cao J, Fu Y, Wang T, Li H, Xu H. Air-laser-based coherent Raman spectroscopy of atmospheric molecules in a filamentary plasma grating. OPTICS LETTERS 2023; 48:4308-4311. [PMID: 37582019 DOI: 10.1364/ol.496658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 07/25/2023] [Indexed: 08/17/2023]
Abstract
Coherent Raman spectroscopy (CRS) with air-laser-based hybrid femtosecond/picosecond (fs/ps) pulses has shown promising potential for remote detection and surveillance of atmospheric species with high temporal and frequency resolution. Here, to enhance the sensitivity and extend the detection distance, we generate the CRS spectra of air molecules in situ in a filamentary plasma grating, and show that the grating can efficiently enhance the intensities of the coherent vibrational Raman lines of N2, O2, and N2 + by 2-3 orders of magnitude at an extended distance. By examining the intensities of the Raman lines, fs-pulsed supercontinuum, and ps-pulsed air laser produced under different grating conditions, we reveal that the optimization of the Raman lines is achieved by the dynamic balance between the supercontinuum-induced vibrational coherence and air-laser-induced polarization of the air species.
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7
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Liu H, Xie H, Li G, Lei H, Zhang Q, Chen Z, Li Z, Wu S, Huang Y, Zhao Z. Destructive interference in N 2+ lasing. OPTICS EXPRESS 2023; 31:17609-17618. [PMID: 37381490 DOI: 10.1364/oe.488389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 04/27/2023] [Indexed: 06/30/2023]
Abstract
We report an unexpected experimental observation in rotation-resolved N2+ lasing that the R-branch lasing intensity from a single rotational state in the vicinity of 391 nm can be greatly stronger than the P-branch lasing intensity summing over the total rotational states at suitable pressures. According to a combined measurement of the dependence of the rotation-resolved lasing intensity on the pump-probe delay and the rotation-resolved polarization, we speculate that the destructive interference can be induced for the spectrally-indistinguishable P-branch lasing due to the propagation effect while the R-branch lasing is little affected due to its discrete spectral property, after precluding the role of rotational coherence. These findings shed light on the air-lasing physics, and provide a feasible route to manipulate air lasing intensity.
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8
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Zhu D, Li C, Sun X, Liu Y, Zhang Y, Gao H. The Effect of Air Turbulence on Vortex Beams in Nonlinear Propagation. SENSORS (BASEL, SWITZERLAND) 2023; 23:1772. [PMID: 36850370 PMCID: PMC9964510 DOI: 10.3390/s23041772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
Vortex beams with orthogonality can be widely used in atmospheric applications. We numerically analyzed the statistical regularities of vortex beams propagating through a lens or an axicon with different series of turbulent air phase screens. The simulative results revealed that the distortion of the transverse intensity was sensitive to the location and the structure constant of the turbulence screen. In addition, the axicon can be regarded as a very useful optical device, since it can not only suppress the turbulence but also maintain a stable beam pattern. We further confirmed that a vortex beam with a large topological charge can suppress the influence of air turbulence. Our outcomes are valuable for many applications in the atmospheric air, especially for optical communication and remote sensing.
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Affiliation(s)
- Di Zhu
- School of Electronics and Information Engineering, Tiangong University, Tianjin 300387, China
- Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems, Tianjin 300387, China
| | - Chunhua Li
- School of Electronics and Information Engineering, Tiangong University, Tianjin 300387, China
- Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems, Tianjin 300387, China
| | - Xiaodong Sun
- School of Electronics and Information Engineering, Tiangong University, Tianjin 300387, China
- Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems, Tianjin 300387, China
| | - Yali Liu
- School of Electronics and Information Engineering, Tiangong University, Tianjin 300387, China
- Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems, Tianjin 300387, China
| | - Yuqi Zhang
- School of Electronics and Information Engineering, Tiangong University, Tianjin 300387, China
- Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems, Tianjin 300387, China
| | - Hui Gao
- School of Physical Science and Technology, Tiangong University, Tianjin 300387, China
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9
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Lu Q, Zhang X, López S, Mei H, Xu L, Liang Q, Houard A, Tikhonchuk V, Mysyrowicz A, Oliva E, Liu Y. Spectral splitting of the lasing emission of nitrogen ions pumped by 800-nm femtosecond laser pulses. OPTICS LETTERS 2023; 48:664-667. [PMID: 36723558 DOI: 10.1364/ol.478025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 12/13/2022] [Indexed: 06/18/2023]
Abstract
We report on a spectral splitting effect of the cavity-less lasing emission of nitrogen ions at 391.4 nm pumped by 800-nm femtosecond laser pulses. It was found that with the increase of the nitrogen gas pressure and pump pulse energy, both R and P branches experience spectral splitting. With an external injected seeding pulse, a similar split spectral line is observed for the amplified emission. In contrast, for the fluorescence radiation, no such spectral splitting phenomenon is observed with much more abundant R branch structures. Our theoretical model considers gas ionization by the pump pulse, the competition of excitation of all relevant electronic and vibrational states, and an amplification of the seeding pulse in the plasma with a population inversion. Our simulation reproduces this spectral splitting effect, which is attributed to the gain saturation resulting in the oscillation of the amplitude of the amplified signal.
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10
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Cao J, Fu Y, Wang S, Chen J, Cong X, Li H, Xu H. Transition from triggered super-radiance to seed amplification in N 2 + lasing. OPTICS LETTERS 2023; 48:526-529. [PMID: 36723522 DOI: 10.1364/ol.478967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 12/19/2022] [Indexed: 06/18/2023]
Abstract
Air lasing induced by laser filamentation opens a new route for research on atmospheric molecular physics and remote sensing. The generation of air lasing is composed of two processes, i.e., building up optical gain of air molecules in femtosecond time scale and emitting coherent radiation in picosecond time scale. Here, we focus on the emission mechanisms of N2 + air lasing and reveal, by examining the intensities and temporal profiles of N2 + lasing at 391 nm generated respectively in a time-varying polarization-modulated and a linearly polarized pump laser field under different nitrogen gas pressures, that the N2 + lasing can emit through either triggered super-radiance or seed amplification. We find that the two pressure-sensitive factors, i.e., the dipole dephasing time T2 and the population inversion density n, determine which of these two mechanisms dominates the N2 + lasing emission process, enabling manipulation of the transition from triggered super-radiance to seed amplification or vice versa. Our findings clarify the emission mechanism of N2 + lasing under different pressures and provide a deeper understanding of N2 + air lasing not only in the establishment of optical gain but also in the lasing emission process.
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11
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Ji L, Liang W, Li D, Chang J, Li D, Zhang L, Xi T, Hao Z. Influence of a pinhole diameter on the experimental determination of critical power for femtosecond filamentation in air. OPTICS EXPRESS 2022; 30:44886-44895. [PMID: 36522902 DOI: 10.1364/oe.475393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 11/04/2022] [Indexed: 06/17/2023]
Abstract
Filamentation of intense femtosecond laser pulses in optical media has attracted great attention due to its various unique characteristics and potential applications. It is an important task to determine the critical power for the filamentation especially in many applications, which can be obtained by evaluating the transmitted pulse energy through a pinhole located in the filamentation region as a function of input laser energy. The pinhole diameter is very crucial to the measurement. However, there is no report on the experimental determination of critical power for filamentation in air by using the pinhole method and the influence of the pinhole diameter on the determination. In this paper, we numerically and experimentally investigate the influence of pinhole diameter on the determination of the filamentation critical power. The obtained critical power tends to a reasonable value as the decrease of the pinhole diameter, because the transmitted energy through the pinhole with a smaller diameter is more sensitive to the change of energy distribution in the beam cross section during the beginning process of filamentation. Under our experimental condition, the pinhole diameter as small as ∼50 µm is applicable to be used to determine the critical power for filamentation of femtosecond laser pulses in air.
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12
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Mazza F, Buurmeijer H, Castellanos L, Bohlin A. Coherent N 2 + emission mediated by coherent Raman scattering for gas-phase thermometry. OPTICS LETTERS 2022; 47:6105-6108. [PMID: 37219183 DOI: 10.1364/ol.476540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 10/30/2022] [Indexed: 05/24/2023]
Abstract
We report on the generation of coherent emission from femtosecond (fs) laser-induced filaments mediated by ultrabroadband coherent Raman scattering (CRS), and we investigate its application for high-resolution gas-phase thermometry. Broadband 35-fs, 800-nm pump pulses generate the filament through photoionization of the N2 molecules, while narrowband picosecond (ps) pulses at 400 nm seed the fluorescent plasma medium via generation of an ultrabroadband CRS signal, resulting in a narrowband and highly spatiotemporally coherent emission at 428 nm. This emission satisfies the phase-matching for the crossed pump-probe beams geometry, and its polarization follows the CRS signal polarization. We perform spectroscopy on the coherent N2 + signal to investigate the rotational energy distribution of the N2 + ions in the excited B2Σu + electronic state and demonstrate that the ionization mechanism of the N2 molecules preserves the original Boltzmann distribution to within the experimental conditions tested.
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13
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Xu L, Lu Q, Tikhonchuk VT, Zhou B, Yang R, Liang Q, He F, Danylo R, Houard A, Mysyrowicz A, Liu Y. Quantum and quasi-classical effects in the strong field ionization and subsequent excitation of nitrogen molecules. OPTICS EXPRESS 2022; 30:38481-38491. [PMID: 36258412 DOI: 10.1364/oe.469492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 09/17/2022] [Indexed: 06/16/2023]
Abstract
The processes leading to the N2 + lasing are rather complex and even the population distribution after the pump laser excitation is unknown. In this paper, we study the population distribution at electronic and vibrational levels in N2 + driven by ultra-short laser pulse at the wavelengths of 800 nm and 400 nm by using the quantum-mechanical time-domain incoherent superposition model based on the time-dependent Schrödinger equation and the quasi-classical model assuming instantaneous ionization injection described by density matrix. It is shown that while both models provide qualitatively similar results, the quasi-classical instantaneous ionization injection model underestimates the population inversions corresponding to the optical transitions at 391 nm, 423 nm and 428 nm due to the assumption of quantum mixed states at the ionization time. A fast and accurate correction to this error is proposed. This work solidifies the theoretical models for population at vibrational states in N2 + and paves the way to uncover the mechanism of the N2 + lasing.
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14
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Qi P, Qian W, Guo L, Xue J, Zhang N, Wang Y, Zhang Z, Zhang Z, Lin L, Sun C, Zhu L, Liu W. Sensing with Femtosecond Laser Filamentation. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22187076. [PMID: 36146424 PMCID: PMC9504994 DOI: 10.3390/s22187076] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 05/25/2023]
Abstract
Femtosecond laser filamentation is a unique nonlinear optical phenomenon when high-power ultrafast laser propagation in all transparent optical media. During filamentation in the atmosphere, the ultrastrong field of 1013-1014 W/cm2 with a large distance ranging from meter to kilometers can effectively ionize, break, and excite the molecules and fragments, resulting in characteristic fingerprint emissions, which provide a great opportunity for investigating strong-field molecules interaction in complicated environments, especially remote sensing. Additionally, the ultrastrong intensity inside the filament can damage almost all the detectors and ignite various intricate higher order nonlinear optical effects. These extreme physical conditions and complicated phenomena make the sensing and controlling of filamentation challenging. This paper mainly focuses on recent research advances in sensing with femtosecond laser filamentation, including fundamental physics, sensing and manipulating methods, typical filament-based sensing techniques and application scenarios, opportunities, and challenges toward the filament-based remote sensing under different complicated conditions.
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Affiliation(s)
- Pengfei Qi
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Tianjin 300350, China
| | - Wenqi Qian
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Tianjin 300350, China
| | - Lanjun Guo
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Tianjin 300350, China
| | - Jiayun Xue
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Tianjin 300350, China
| | - Nan Zhang
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Tianjin 300350, China
| | - Yuezheng Wang
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Tianjin 300350, China
| | - Zhi Zhang
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin 300350, China
| | - Zeliang Zhang
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Tianjin 300350, China
| | - Lie Lin
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin 300350, China
| | - Changlin Sun
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Tianjin 300350, China
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
| | - Liguo Zhu
- National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
| | - Weiwei Liu
- Institute of Modern Optics, Eye Institute, Nankai University, Tianjin 300350, China
- Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin 300350, China
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15
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Kleine C, Winghart MO, Zhang ZY, Richter M, Ekimova M, Eckert S, Vrakking MJJ, Nibbering ETJ, Rouzée A, Grant ER. Electronic State Population Dynamics upon Ultrafast Strong Field Ionization and Fragmentation of Molecular Nitrogen. PHYSICAL REVIEW LETTERS 2022; 129:123002. [PMID: 36179157 DOI: 10.1103/physrevlett.129.123002] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 07/20/2022] [Accepted: 08/10/2022] [Indexed: 06/16/2023]
Abstract
Air lasing from single ionized N_{2}^{+} molecules induced by laser filamentation in air has been intensively investigated and the mechanisms responsible for lasing are currently highly debated. We use ultrafast nitrogen K-edge spectroscopy to follow the strong field ionization and fragmentation dynamics of N_{2} upon interaction with an ultrashort 800 nm laser pulse. Using probe pulses generated by extreme high-order harmonic generation, we observe transitions indicative of the formation of the electronic ground X^{2}Σ_{g}^{+}, first excited A^{2}Π_{u}, and second excited B^{2}Σ_{u}^{+} states of N_{2}^{+} on femtosecond timescales, from which we can quantitatively determine the time-dependent electronic state population distribution dynamics of N_{2}^{+}. Our results show a remarkably low population of the A^{2}Π_{u} state, and nearly equal populations of the X^{2}Σ_{g}^{+} and B^{2}Σ_{u}^{+} states. In addition, we observe fragmentation of N_{2}^{+} into N and N^{+} on a timescale of several tens of picoseconds that we assign to significant collisional dynamics in the plasma, resulting in dissociative excitation of N_{2}^{+}.
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Affiliation(s)
- Carlo Kleine
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Straße 2a, 12489 Berlin, Germany
| | - Marc-Oliver Winghart
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Straße 2a, 12489 Berlin, Germany
| | - Zhuang-Yan Zhang
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Straße 2a, 12489 Berlin, Germany
| | - Maria Richter
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Straße 2a, 12489 Berlin, Germany
| | - Maria Ekimova
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Straße 2a, 12489 Berlin, Germany
| | - Sebastian Eckert
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Straße 2a, 12489 Berlin, Germany
| | - Marc J J Vrakking
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Straße 2a, 12489 Berlin, Germany
| | - Erik T J Nibbering
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Straße 2a, 12489 Berlin, Germany
| | - Arnaud Rouzée
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Straße 2a, 12489 Berlin, Germany
| | - Edward R Grant
- Department of Chemistry and Department of Physics and Astronomy, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
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16
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Rastegari A, Diels JC, Kamer B, Liu LR, Arissian L. Measurement of delayed fluorescence in N 2 + with a streak camera. OPTICS EXPRESS 2022; 30:31498-31508. [PMID: 36242229 DOI: 10.1364/oe.468835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/03/2022] [Indexed: 06/16/2023]
Abstract
Using a streak camera, we directly measure time- and space-resolved dynamics of N 2 + emission from a self-seeded filament. Fluorescence emission does not start with ionization, but with a delay in the tenth of ps range.
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17
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Zhuang C, Zhang X, Lu Q, Liu Y. Optical amplification and gain dynamics of cavity-free lasing of argon pumped by ultraviolet femtosecond pulses. OPTICS EXPRESS 2022; 30:17156-17163. [PMID: 36221544 DOI: 10.1364/oe.455743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 04/18/2022] [Indexed: 06/16/2023]
Abstract
Argon gas excited by resonant femtosecond ultraviolet pulses gives rise to cavity-free lasing emission in the near-infrared (NIR) range. Here we reported on a pump-probe study of the optical gain of this lasing phenomenon. With the injection of an external seeding pulse, the forward signal was significantly enhanced, confirming the existence of optical gain. The temporal dynamics of the optical gain were characterized by a time-resolved measurement. It was found that the optical gain decays on a time scale of ∼ 10 ps and it does not present a significant dependence on the gas pressures. Moreover, the intensity of the forward NIR emission signal shows a linear dependence on the gas pressure. These features suggest that the nature of this forward NIR radiation is amplified spontaneous emission, not superradiance when multiple-photon resonant excitation is involved.
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18
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Qasim M, Zimin DA, Yakovlev VS. Optical Gain in Solids after Ultrafast Strong-Field Excitation. PHYSICAL REVIEW LETTERS 2021; 127:087401. [PMID: 34477433 DOI: 10.1103/physrevlett.127.087401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/21/2021] [Accepted: 07/23/2021] [Indexed: 06/13/2023]
Abstract
Multiphoton excitation of a solid by a few-cycle, intense laser pulse forms a very nonequilibrium distribution of charge carriers, where occupation probabilities do not necessarily decrease with energy. Within a fraction of the pulse, significant population inversion can emerge between pairs of valence-band states with a dipole-allowed transition between them. This population inversion leads to stimulated emission in a laser-excited solid at frequencies where the unperturbed solid is transparent. We establish the optimal conditions for observing this kind of strong-field-induced optical gain.
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Affiliation(s)
- Muhammad Qasim
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, Garching 85748, Germany and Ludwig-Maximilians-Universität, Am Coulombwall 1, Garching 85748, Germany
| | - Dmitry A Zimin
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, Garching 85748, Germany and Ludwig-Maximilians-Universität, Am Coulombwall 1, Garching 85748, Germany
| | - Vladislav S Yakovlev
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, Garching 85748, Germany and Ludwig-Maximilians-Universität, Am Coulombwall 1, Garching 85748, Germany
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19
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Wan YX, Fu BT, Xie HQ, Yu SP, Lei HB, Zhang FB, Zhang ZH, Qiao LL, Li GH, Zhao J, Zhao ZX, Yao JP, Cheng Y. Observation of rotational coherence in an excited state of CO . OPTICS LETTERS 2021; 46:3893-3896. [PMID: 34388768 DOI: 10.1364/ol.432315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 07/12/2021] [Indexed: 06/13/2023]
Abstract
The vacuum ultraviolet (VUV) radiation is generated in the strong-field-ionized CO molecules through 2+1 resonance excitation with two-color femtosecond laser pulses. When scanning the relative delay between two pump pulses, the rotational-resolved VUV radiations show periodic oscillations lasting as long as 500 ps. Fourier analysis reveals that these oscillations correspond to rotational beat frequencies of the A2Πi state of CO+, which is the result of multi-channel interference during the resonant excitation process. High resolution of Fourier transform spectra up to 0.067cm-1 allows us to obtain the fine energy levels of the A2Πi state. The theoretical calculation is in good agreement with the experimental observation. This work reveals the rotational coherence of the ionic excited state and shows the prospect of rotational coherence spectroscopy in measuring fine structures of molecular ions.
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20
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Fu Y, Cao J, Wang S, Chen S, Zang H, Li H, Lötstedt E, Ando T, Iwasaki A, Yamanouchi K, Xu H. Extremely enhanced N 2+ lasing in a filamentary plasma grating in ambient air. OPTICS LETTERS 2021; 46:3404-3407. [PMID: 34264224 DOI: 10.1364/ol.428065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Cavity-free air lasing offers a promising route towards the realization of atmospheric lasers for various applications such as remote sensing and standoff spectroscopy; however, achieving efficient generation and control of air lasing in ambient air is still a challenge. Here we show the experimental realization of a giant lasing enhancement by three to four orders of magnitude in ambient air for the self-seeded N2+ lasing at 428 nm, assigned to the B2Σu+(ν'=0) and X2Σg+(ν''=1) emission, by modulating the spatiotemporal overlap of ultrashort near-infrared control-pump pulses in a filamentary plasma grating; meanwhile, the spontaneous emission from the same transition is only enhanced by three to four times. We find that this enhancement is sensitive to the relative polarization and interference time of the two pulses, and reveal that the formation of the plasma grating induces different population variations in the B2Σu+(ν'=0) and X2Σg+(ν''=1) levels, resulting in an enormous population inversion between the two levels, thereby a higher gain for the giant enhancement of N2+ lasing in ambient air.
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21
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Danylo R, Lambert G, Liu Y, Tikhonchuk V, Houard A, Mysyrowicz A. Time-resolved study of laser emission in nitrogen gas pumped by two near IR femtosecond laser pulses. OPTICS LETTERS 2021; 46:1253-1256. [PMID: 33720160 DOI: 10.1364/ol.414863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 01/18/2021] [Indexed: 06/12/2023]
Abstract
The time profile of a lasing signal at 391.4 nm emitted by a weakly ionized gas of nitrogen molecules at low pressure is measured under double excitation with intense femtosecond laser pulses at 800 nm. An abrupt decrease in emission occurs at the time of arrival of the second pulse. It is explained by a transfer of population from ground to first excited ionic level and by a disruption of coherence, terminating the conditions for lasing in a V-scheme without population inversion.
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22
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Miao Z, Zheng W, Wang Y, Dai C, Li Z, Wu C. Optical amplification from high vibrational states of ionized nitrogen molecules generated by 800-nm femtosecond laser pulses. OPTICS EXPRESS 2021; 29:2279-2287. [PMID: 33726426 DOI: 10.1364/oe.414843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/01/2021] [Indexed: 06/12/2023]
Abstract
We experimentally investigated the interaction between nitrogen molecules and intense femtosecond laser pulses. When irradiated by an 800-nm pump laser and a delayed 355-nm seed laser, the spectral lines around 353.3 nm and 353.8 nm are observed to be greatly amplified, no matter whether the pump laser is circularly or linearly polarized. The two spectral lines correspond to the transition of N2+ (B, ν' = 5 → X, ν = 4) and N2+ (B, ν' = 4 → X, ν = 3), respectively. In comparison with the spectral lines related with ground vibrational states of nitrogen molecular ion, the observed amplification exhibits different polarization dependence of the pump laser. This distinctive change can be explained by the population variation of high vibrational states caused by the pump laser with different polarizations.
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23
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Li Z, Kuan YH, Mu X, Miao Z, Wu C, Liao WT. Ramsey interferometry through coherent A2Πu- X2Σg+- B2Σu+ coupling and population transfer in N2+ air laser. OPTICS LETTERS 2020; 45:6587-6590. [PMID: 33325846 DOI: 10.1364/ol.401800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 10/26/2020] [Indexed: 06/12/2023]
Abstract
Motivated by the hot debate on the mechanism of laser-like emission at 391 nm from N2 gas irradiated by a strong 800 nm pump laser and a weak 400 nm seed laser, we theoretically study the temporal profile, optical gain, and modulation of the 391 nm signal from N2+. Our calculation sheds light on the long standing controversy on whether population inversion is indispensable for optical gain and show the Ramsey fringes of the emission intensity at 391 nm formed by additionally injecting another 800 nm pump or 400 nm seed, which provides strong evidence for the coherence driven modulation of transition dipole moment and population transfer between the A2Πu(ν=2)-X2Σg+ states and the B2Σu+(ν=0)-X2Σg+ states. Our results show that the 391 nm optical gain is susceptible to the population inversion within N2+ states manipulated by the Ramsey technique and thus clearly reveal their symbiosis. This study reveals not only the physical picture of producing N2+ population inversion but also versatile control of the N2+ air laser.
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24
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Li H, Pan S, Chen F, Sun F, Li Z, Xu H, Wu J. Optimization of N 2+ lasing by waveform-controlled polarization-skewed pulses. OPTICS LETTERS 2020; 45:6591-6594. [PMID: 33325847 DOI: 10.1364/ol.410153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 11/07/2020] [Indexed: 05/20/2023]
Abstract
Optical ionization of N2 and subsequent population redistribution among the ground and excited states of N2+ in an intense laser field are commonly accepted to be fundamentally responsible for the generation of N2+ lasing. By finely controlling this two-step process, the optimization of N2+ lasing is possibly achieved. Here, we design a waveform-controlled polarization-skewed (PS) pumping pulse, in which the leading and falling edges are orthogonally polarized, and their relative field strength and phase can be well controlled. We demonstrate that precise manipulation of the N2+ lasing at 391 nm and 428 nm emissions can be achieved by modulating both the relative phase and amplitudes of the two orthogonally polarized components of the pumping PS pulse. We find that the optimization of N2+ lasing depends not only on the competitive balance between the ionization and post-ionization coupling that varies in different pumping energies but also on the phase with the maximum intensity appearing at the phase of nπ. Orders of magnitude enhancement in the N2+ lasing intensity is observed as the phase changes from (n+1/2)π to nπ. The PS pulse with a controllable spatiotemporal waveform provides us a robust and straightforward tool to efficiently enhance the N2+ lasing emission.
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25
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Understanding the Seeding Pulse-Induced Optical Amplification in
N
2
+
Pumped by 800 NM Femtosecond Laser Pulses. PHOTONICS 2020. [DOI: 10.3390/photonics7040099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nitrogen ions pumped by intense femtosecond laser pulses present an optical gain at 391.4 nm, evident by energy amplification of an injected resonant seeding pulse. We report a time-resolved measurement of the amplification process with seeding pulses having varying intensities. It is found that the amplification factor depends on the intensity of the seeding pulse and the effective temporal window for the optical gain becomes longer by applying more intense seeding pulses. These two features are in sharp contrast with classic pump-probe experiments, pinpointing the crucial role of macroscopic coherence and its dynamics during the lasing process. We further measure the temporal profile of the amplified emission for seeding pulse injected at different time delays. A complicated temporal behavior is observed, which highlights the nature of the superfluorescence.
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26
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Li G, Xie H, Zhang Q, Lei H, Zhou X, Wang X, Chen Z, Zhao Z. Enhanced resonant vibrational Raman scattering of N 2+ induced by self-seeding ionic lasers created in polarization-modulated intense laser fields. OPTICS LETTERS 2020; 45:5616-5619. [PMID: 33001962 DOI: 10.1364/ol.403110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/05/2020] [Indexed: 06/11/2023]
Abstract
We report on an experimental investigation of the five vibrational Raman lines at 358 nm, 388 nm, 391 nm, 428 nm, and 471 nm of N2+ resonantly driven by the self-seeding ionic lasers generated by a polarization-modulated (PM) or alternatively a linearly polarized (LP) femtosecond laser. It was found that the spectral intensities of several Raman lines can be dramatically enhanced by exploiting the PM laser pulses in comparison to the LP laser pulses. The evaluated Raman conversion efficiency reaches ∼10-2 for some lasing lines at suitable pressures. Moreover, the role of interplay between the seed amplification and the resonant vibrational Raman scattering processes in inducing the gain of N2+ lasing is characterized for the first time. The developed vibrational Raman spectroscopy with intense ultrafast lasers provides an additional approach to interrogate the products in a femtosecond filament, and it therefore can be a powerful tool for identifying chemical species at remote distances in the atmosphere.
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27
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Zheng W, Miao Z, Dai C, Wang Y, Liu Y, Gong Q, Wu C. Formation Mechanism of Excited Neutral Nitrogen Molecules Pumped by Intense Femtosecond Laser Pulses. J Phys Chem Lett 2020; 11:7702-7708. [PMID: 32845646 DOI: 10.1021/acs.jpclett.0c02337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Backward amplified spontaneous emission of neutral nitrogen molecules has been reported from laser-induced plasma filaments. The cavity-free UV emission has great potential applications in remote atmospheric sensing. However, the formation mechanism for the excited nitrogen molecules inside filaments remains controversial. Here we study the formation mechanism of excited nitrogen molecules pumped by intense femtosecond laser pulses. After modification of the electron energy distribution by inclusion of the recollision between the electron and its parent ion as well as modification of the electron collision cross section by inclusion of the secondary electron contribution, the theoretical calculations reproduce the experimental observations very well. The results clearly demonstrate that excited nitrogen molecules are generated through collisions between energetic electrons and neutral nitrogen molecules.
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Affiliation(s)
- Wei Zheng
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhiming Miao
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Chen Dai
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Yang Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Yi Liu
- Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
- CAS Center for Excellence in Ultra-Intense Laser Science, Shanghai 201800, China
| | - Qihuang Gong
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Chengyin Wu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
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28
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Danylo R, Lambert G, Liu Y, Tikhonchuk V, Houard A, Mysyrowicz A. Quantum erasing of laser emission in N2. OPTICS LETTERS 2020; 45:4670-4673. [PMID: 32870827 DOI: 10.1364/ol.395261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 07/18/2020] [Indexed: 06/11/2023]
Abstract
Cavity-free lasing of N2+ induced by a femtosecond laser pulse at 800 nm is nearly totally suppressed by a delayed twin control pulse. We explain this surprising effect within the V-scheme of lasing without population inversion. A fast transfer of population between nitrogen ionic states X2Σg+ and A2Πu, induced by the second pulse, terminates the conditions for amplification in the system. The appearance of short lasing bursts at delays corresponding to revivals of rotational wave packets is explained along the same lines.
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29
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Fu Y, Chen S, Wang S, Zhang W, Yao D, Zang H, Li H, Xu H. Asymmetric enhancement of N 2+ lasing in intense, birefringence-modulating elliptical laser fields. OPTICS EXPRESS 2020; 28:23274-23283. [PMID: 32752326 DOI: 10.1364/oe.389284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 07/14/2020] [Indexed: 06/11/2023]
Abstract
We experimentally demonstrate an asymmetric enhancement of the N2+ lasing at 391 nm for the transition between the B2Σu+ (v = 0) and X2Σg+ (v" = 0) states in an intense laser field with the ellipticity, ε, modulated by a 7-order quarter-wave plate (7-QWP). It is found that when the 7-QWP is rotated from α = 0 to 90°, where α is the angle between the polarization direction of the input laser and the slow axis of the 7-QWP, the intensity of the 391-nm lasing is optimized at ε ∼ 0.3 with α∼ 10°-20° and 70°-80° respectively, but the optimization intensity at α∼ 10°-20° is about 4 times smaller than that at α∼ 70°-80°. We interpret the asymmetric enhancement based on a post-ionization coupling model, in which the birefringence of the 7-QWP induces an opposite change in the relative amplitudes of the ordinary (Eo) and extraordinary (Ee) electric components under the two conditions, so that the same temporal separation of Eo and Ee leads to a remarkably different coupling strength for the population transfer from the X2Σg+ (v "=0) to A2Πu (v '=2) states.
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30
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Li H, Lötstedt E, Li H, Zhou Y, Dong N, Deng L, Lu P, Ando T, Iwasaki A, Fu Y, Wang S, Wu J, Yamanouchi K, Xu H. Giant Enhancement of Air Lasing by Complete Population Inversion in N_{2}^{+}. PHYSICAL REVIEW LETTERS 2020; 125:053201. [PMID: 32794853 DOI: 10.1103/physrevlett.125.053201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 07/09/2020] [Indexed: 06/11/2023]
Abstract
A fine manipulation of population transfer among molecular quantum levels is a key technology for control of molecular processes. When a light field intensity is increased to the TW-PW cm^{-2} level, it becomes possible to transfer a population to specific excited levels through nonlinear light-molecule interaction, but it has been a challenge to control the extent of the population transfer. We deplete the population in the X^{2}Σ_{g}^{+}(v=0) state of N_{2}^{+} almost completely by focusing a dual-color (800 nm and 1.6 μm) intense femtosecond laser pulse in a nitrogen gas, and make the intensity of N_{2}^{+} lasing at 391 nm enhanced by 5-6 orders of magnitude. By solving a time-dependent Schrödinger equation describing the population transfer among the three lowest electronic states of N_{2}^{+}, we reveal that the X^{2}Σ_{g}^{+}(v=0) population is depleted by the vibrational Raman excitation followed by the electronic excitation A^{2}Π_{u}(v=2,3,4)←X^{2}Σ_{g}^{+}(v=1)←X^{2}Σ_{g}^{+}(v=0), resulting in the excessive population inversion between the B^{2}Σ_{u}^{+}(v=0) and X^{2}Σ_{g}^{+}(v=0) states. Our results offer a promising route to efficient population transfer among vibrational and electronic levels of molecules by a precisely designed intense laser field.
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Affiliation(s)
- Hanxiao Li
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Erik Lötstedt
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Helong Li
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Yan Zhou
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Nana Dong
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Lunhua Deng
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Peifen Lu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Toshiaki Ando
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Atsushi Iwasaki
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yao Fu
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Siqi Wang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Jian Wu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Kaoru Yamanouchi
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Huailiang Xu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
- CAS Center for Excellence in Ultra-intense Laser Science, Shanghai 201800, China
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31
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Lei H, Li G, Xie H, Zhang Q, Wang X, Zhao J, Chen Z, Zhao Z. Mechanism and control of rotational coherence in femtosecond laser-driven N2. OPTICS EXPRESS 2020; 28:22829-22843. [PMID: 32752537 DOI: 10.1364/oe.398888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/10/2020] [Indexed: 06/11/2023]
Abstract
We investigate the formation of rotational coherence of N2+ resonantly interacting with an intense femtosecond laser field by numerical simulations based on a strong-field ionization-coupling model described with the density matrix formalism. The created N2+ system is unique in many aspects: the variable total population within the pump duration due to the intensity-dependent ionization injection, the readily accessible resonance owing to the effect of Stark shift, and the involvement of a few dozen of quantum states. By regarding the N2+ system as an open and non-stationary Λ-type cascaded multi-level system, we quantitatively studied the dependence of rotational coherence in different electronic-vibrational states of N2+ on the alignment angle θ and the pumping intensity. Our simulation results indicate that the quantum coherence between the neighbouring rotational states of J, J+2 in the vibrational state ν=0, 1 of the ground state of N2+ can be changed from a negative to a positive. The significant contribution of rotational coherence to inducing an extra gain or absorption of N2+ air lasing is further verified by solving the Maxwell's propagating equation. The finding provides crucial clues on how to manipulate N2+ lasing by controlling the rotational coherence and paves the way to studying strong-field quantum optics effects such as lasing without inversion and electromagnetically induced transparency in molecular ionic systems.
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32
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Zhao X, Nolte S, Ackermann R. Lasing of N2+ induced by filamentation in air as a probe for femtosecond coherent anti-Stokes Raman scattering. OPTICS LETTERS 2020; 45:3661-3664. [PMID: 32630924 DOI: 10.1364/ol.391989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 05/29/2020] [Indexed: 06/11/2023]
Abstract
We investigated ultrashort pulse filamentation and lasing action of N2+ for pump-probe experiments in gases. Using femtosecond coherent anti-Stokes Raman scattering, the white-light supercontinuum generated in the filament was used to excite ro-vibrational Raman transitions in air, CO2 and CH4. We show that the lasing pulse acts as a probe for the excited levels by detecting the corresponding anti-Stokes Raman spectroscopy signals. This feature may be applied to remote sensing applications, as the temporal and spatial alignment of the probe beam and the filament is intrinsically provided.
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33
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Su Q, Sun L, Chu C, Zhang Z, Zhang N, Lin L, Zeng Z, Kosareva O, Liu W, Chin SL. Effect of Molecular Orbital Angular Momentum on the Spatial Distribution of Fluorescence during Femtosecond Laser Filamentation in Air. J Phys Chem Lett 2020; 11:730-734. [PMID: 31898909 DOI: 10.1021/acs.jpclett.9b03025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nonuniform azimuthal distribution of N2+ fluorescence emitted from the femtosecond laser filament in air was discovered. The fluorescence is stronger when the detector is placed perpendicular or parallel to the laser polarization. The experimental results have been confirmed by the theoretical calculation that the azimuthal distribution of fluorescence is reproduced by the convolution of the transition of the dipole and the molecular alignment in the strong laser field. The results would provide new insight into laser-molecule interactions during filamentation, which are important in practice for remote sensing using filamentation.
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Affiliation(s)
- Qiang Su
- Institute of Modern Optics, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology , Nankai University , Tianjin 300071 , People's Republic of China
| | - Lu Sun
- Institute of Modern Optics, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology , Nankai University , Tianjin 300071 , People's Republic of China
| | - Chunyue Chu
- Institute of Modern Optics, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology , Nankai University , Tianjin 300071 , People's Republic of China
| | - Zhi Zhang
- Institute of Modern Optics, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology , Nankai University , Tianjin 300071 , People's Republic of China
| | - Nan Zhang
- Institute of Modern Optics, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology , Nankai University , Tianjin 300071 , People's Republic of China
| | - Lie Lin
- Institute of Modern Optics, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology , Nankai University , Tianjin 300071 , People's Republic of China
| | - Zhinan Zeng
- State Key Laboratory of High Field Laser Physics , Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences , Shanghai 201800 , China
| | - Olga Kosareva
- Institute of Modern Optics, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology , Nankai University , Tianjin 300071 , People's Republic of China
- Faculty of Physics & International Laser Center , Lomonosov Moscow State University , Moscow 119991 , Russia
| | - Weiwei Liu
- Institute of Modern Optics, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology , Nankai University , Tianjin 300071 , People's Republic of China
| | - See Leang Chin
- Centre d'Optique, Photonique et Laser (COPL) et le Département de Physique, de Génie Physique et d'Optique , Université Laval , Québec G1K 7P4 , Canada
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34
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Ando T, Lötstedt E, Iwasaki A, Li H, Fu Y, Wang S, Xu H, Yamanouchi K. Rotational, Vibrational, and Electronic Modulations in N_{2}^{+} Lasing at 391 nm: Evidence of Coherent B^{2}Σ_{u}^{+}-X^{2}Σ_{g}^{+}-A^{2}Π_{u} Coupling. PHYSICAL REVIEW LETTERS 2019; 123:203201. [PMID: 31809116 DOI: 10.1103/physrevlett.123.203201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 08/23/2019] [Indexed: 06/10/2023]
Abstract
We investigate lasing of a N_{2} gas induced by intense few-cycle near-IR laser pulses. By the pump-probe measurements, we reveal that the intensity of the B^{2}Σ_{u}^{+}-X^{2}Σ_{g}^{+} lasing emission of N_{2}^{+} oscillates at high (0.3-0.5 PHz), medium (50-75 THz), and low (∼3 THz) frequencies, corresponding to the energy separations between the rovibrational levels of the A^{2}Π_{u} and X^{2}Σ_{g}^{+} states. By solving the time-dependent Schrödinger equation, we reproduce the oscillations in the three different frequency ranges and show that the coherent population transfer among the three electronic states of N_{2}^{+} creates the population inversion between the B^{2}Σ_{u}^{+} and X^{2}Σ_{g}^{+} states, resulting in the lasing at 391 nm.
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Affiliation(s)
- Toshiaki Ando
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Erik Lötstedt
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Atsushi Iwasaki
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Helong Li
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Yao Fu
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Siqi Wang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Huailiang Xu
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Kaoru Yamanouchi
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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35
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Zheng W, Miao Z, Zhang L, Wang Y, Dai C, Zhang A, Jiang H, Gong Q, Wu C. Enhanced Coherent Emission from Ionized Nitrogen Molecules by Femtosecond Laser Pulses. J Phys Chem Lett 2019; 10:6598-6603. [PMID: 31603688 DOI: 10.1021/acs.jpclett.9b02581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The forward emission spectra were experimentally measured for ionized nitrogen molecules by an 800 nm pump laser and a delayed seed laser. It was found that emission lines around both 428 and 391 nm are greatly enhanced upon use of a 391 or 428 nm seed laser. The emission lines around 391 and 428 nm can be assigned to the rotational transitions of N2+ [B2Σu+(v' = 0) → X2Σg+(v = 0)] and N2+ [B2Σu+(v' = 0) → X2Σg+(v = 1)], respectively. They originate from seed-induced superfluorescence and resonant stimulated Raman scattering. The genetic algorithm was utilized to simulate the experimental observations and determine the relative population of B2Σu+(v' = 0), X2Σg+(v = 1), and X2Σg+(v = 0). The result verifies that vibrational population inversion is achieved between B2Σu+(v' = 0) and X2Σg+(v = 0) by the 800 nm pump laser. Our finding provides new insights into controlling the coherent emission of ionized nitrogen molecules, which has promising application in filamentation-based remote atmospheric sensing.
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Affiliation(s)
- Wei Zheng
- State Key Laboratory for Mesoscopic Physics, School of Physics , Peking University , Beijing 100871 , China
| | - Zhiming Miao
- State Key Laboratory for Mesoscopic Physics, School of Physics , Peking University , Beijing 100871 , China
| | - Linlin Zhang
- State Key Laboratory for Mesoscopic Physics, School of Physics , Peking University , Beijing 100871 , China
| | - Yang Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics , Peking University , Beijing 100871 , China
| | - Chen Dai
- State Key Laboratory for Mesoscopic Physics, School of Physics , Peking University , Beijing 100871 , China
| | - An Zhang
- State Key Laboratory for Mesoscopic Physics, School of Physics , Peking University , Beijing 100871 , China
| | - Hongbing Jiang
- State Key Laboratory for Mesoscopic Physics, School of Physics , Peking University , Beijing 100871 , China
- Collaborative Innovation Center of Extreme Optics , Shanxi University , Taiyuan , Shanxi 030006 , China
| | - Qihuang Gong
- State Key Laboratory for Mesoscopic Physics, School of Physics , Peking University , Beijing 100871 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100871 , China
- Collaborative Innovation Center of Extreme Optics , Shanxi University , Taiyuan , Shanxi 030006 , China
- Frontiers Science Center for Nano-optoelectronics , Peking University , Beijing 100871 , China
| | - Chengyin Wu
- State Key Laboratory for Mesoscopic Physics, School of Physics , Peking University , Beijing 100871 , China
- Collaborative Innovation Center of Quantum Matter , Beijing 100871 , China
- Collaborative Innovation Center of Extreme Optics , Shanxi University , Taiyuan , Shanxi 030006 , China
- Frontiers Science Center for Nano-optoelectronics , Peking University , Beijing 100871 , China
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36
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Ran P, Li G, Liu T, Hou H, Luo SN. Collision-mediated ultrafast decay of N 2 fluorescence during fs-laser-induced filamentation. OPTICS EXPRESS 2019; 27:19177-19187. [PMID: 31503681 DOI: 10.1364/oe.27.019177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 05/26/2019] [Indexed: 06/10/2023]
Abstract
We investigate experimentally spatiotemporal characteristics of fluorescence emission from fs-laser-induced filaments in air. Emissions accompanying the transitions of N2 (C3Πu-B3Πg) and N 2+ (B2Σu+-X2Σg+) are dominant. The decay dynamics of fluorescence from different radial positions and longitudinal sections of a filament column are obtained along with high resolution spectra. A decay curve contains two exponential components: a fast one (with a decay time constant ∼10s ps), and a slow one (∼sub-ns). The lifetime of the N 2 fluorescence is about three orders shorter than its spontaneous emission lifetime, indicating that most of the N 2 molecules in the excited state (C3Πu) are de-excited through collision. Different de-excitation mechanisms of N 2 (C3Πu) molecules contributing to fluorescence decay constants, e.g., the e --N2, N 2-N2, and O 2-N2 collisions, are elucidated. We analyze the variations of decay constants together with corresponding fluorescence intensities, and obtain temperature distributions by fitting band spectra of N 2 molecules and N 2+ ions with a synthetic spectral model. Our results suggest that the fast and slow decay processes originate from the e --N2 and O 2-N2 collisions, respectively.
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Xu B, Yao J, Wan Y, Chen J, Liu Z, Zhang F, Chu W, Cheng Y. Vibrational Raman scattering from coherently excited molecular ions in a strong laser field. OPTICS EXPRESS 2019; 27:18262-18272. [PMID: 31252772 DOI: 10.1364/oe.27.018262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 05/31/2019] [Indexed: 06/09/2023]
Abstract
We report on a pump-probe investigation of vibrational Raman scattering from coherently excited N2+ ions. It is found that the Raman signals produced by the inelastic scattering of the probe pulse from molecular ions can be dramatically enhanced when the probe laser is resonant with electronic transitions in N2+ ions. The Raman signal can be amplified at 428 nm wavelength due to the presence of population inversion in N2+ ions.
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Zhang A, Lei M, Gao J, Wu C, Gong Q, Jiang H. Subfemtosecond-resolved modulation of superfluorescence from ionized nitrogen molecules by 800-nm femtosecond laser pulses. OPTICS EXPRESS 2019; 27:14922-14930. [PMID: 31163933 DOI: 10.1364/oe.27.014922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 05/02/2019] [Indexed: 06/09/2023]
Abstract
Superfluorescence emission around 391 nm is generated when nitrogen molecules are irradiated by a strong 800-nm pump laser and a delayed seed laser. The emission corresponds to the transition between N2+(B2Σu+,ν″=0) and N2+(X2Σg+,ν=0). When another weak 800-nm probe laser is injected and scanned after the pump laser, the superfluorescence intensity is observed to exhibit periodical modulation. The period is determined to be ~2.63 fs, corresponding to the transition frequency between N2+(A2Πu,ν'=2) and N2+(X2Σg+,ν=0). Based on theoretical derivation, these observations can be attributed to the laser-induced population transfer and polarization variation between the relevant electronic states of ionized nitrogen molecules.
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Zhang A, Liang Q, Lei M, Yuan L, Liu Y, Fan Z, Zhang X, Zhuang S, Wu C, Gong Q, Jiang H. Coherent modulation of superradiance from nitrogen ions pumped with femtosecond pulses. OPTICS EXPRESS 2019; 27:12638-12646. [PMID: 31052802 DOI: 10.1364/oe.27.012638] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/11/2019] [Indexed: 06/09/2023]
Abstract
Singly ionized nitrogen molecules in ambient air pumped by 800 nm femtosecond laser give rise to superradiant emission. Here, we study this superradiance by injecting a pair of resonant seeding pulses at different intensity ratios inside the nitrogen gas plasma. Strong modulation of the 391.4 nm superradiant emission with a period of 1.3 fs is observed when the delay between the two seeding pulses is finely tuned. The modulation contrast is increased and then decreased with the delay time when the second seed pulse is stronger than the first one, and the maximum modulation contrast occurs at longer delay time when the second seeding pulse is stronger. This reveals the increase of the macroscopic polarization with time after the seeding pulse. Moreover, these observations provide a new level of control on the "air lasing" based on nitrogen ions, which can find potential applications in optical remote sensing.
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40
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Li H, Hou M, Zang H, Fu Y, Lötstedt E, Ando T, Iwasaki A, Yamanouchi K, Xu H. Significant Enhancement of N_{2}^{+} Lasing by Polarization-Modulated Ultrashort Laser Pulses. PHYSICAL REVIEW LETTERS 2019; 122:013202. [PMID: 31012701 DOI: 10.1103/physrevlett.122.013202] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Indexed: 06/09/2023]
Abstract
We show that the intensity of self-seeded N_{2}^{+} lasing at 391 nm, assigned to the B^{2}Σ_{u}^{+}(v^{'}=0)→X^{2}Σ_{g}^{+}(v^{''}=0) emission, is enhanced by 2 orders of magnitude by modulating in time the polarization of an intense ultrashort near-IR (40 fs, 800 nm) laser pulse with which N_{2} is irradiated. We find that this dramatic enhancement of the 391 nm lasing is sensitive to the temporal variation of the polarization state within the laser pulse while the intensity of the spontaneous fluorescence emission at 391 nm is kept constant when the polarization state varies. We conclude that a postionization multiple-state coupling, through which the population can be transferred from the X^{2}Σ_{g}^{+} state of N_{2}^{+} to the first electronically excited A^{2}Π_{u} state, leads to the depletion of the population in the X^{2}Σ_{g}^{+} state, and consequently, to the population inversion between the X^{2}Σ_{g}^{+} state and the B^{2}Σ_{u}^{+} state.
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Affiliation(s)
- Helong Li
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Mengyao Hou
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Hongwei Zang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Yao Fu
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Erik Lötstedt
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Toshiaki Ando
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Atsushi Iwasaki
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kaoru Yamanouchi
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Huailiang Xu
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
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41
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Zhang Y, Lotstedt E, Yamanouchi K. Population inversion in laser-driven N 2+. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201920507010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The time-dependent population transfer process of N2+ generated in an intense laser pulse has been investigated using the quasi-stationary Floquet theory by assuming that N2+ experiences an intense laser pulse with the sudden turn-on. A light-dressed B state is formed with a significant amount of population when pulse is suddenly turned on and is adiabatically transformed to the vibrational ground state (v = 0) of the field-free B state when the pulse vanishes. In addition, a part of the population is transferred to the electronically excited A state through one-photon resonance, which also contributes to decreasing the final population in the X state, facilitating the population inversion between the B state and the X state.
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42
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Aluminum-target-assisted femtosecond-laser-filament-induced water condensation and snow formation in a cloud chamber. Sci Rep 2018; 8:18080. [PMID: 30591707 PMCID: PMC6308231 DOI: 10.1038/s41598-018-36548-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 11/20/2018] [Indexed: 11/08/2022] Open
Abstract
We compare the water condensation and snow formation induced by a femtosecond laser filament with that when the filament is assisted by an aluminum target located at different positions along the filament. We reveal that the laser-filament-induced water condensation and snow formation assisted by the aluminum target are more efficient compared with those obtained without the assistance of the aluminum target. We find that the mass of the snow induced by the laser filament is the largest when the aluminum target is located at the end of the filament, smaller when it is at the middle of the filament, and the smallest at the beginning of the filament. These findings indicate that a higher plasma density and the generation of vortex pairs below the filament are important for enhancing the efficiency and yield of the laser-induced water condensation and precipitation. The higher plasma density provides more cloud condensation nuclei and facilitates the water condensation; vortex pairs below the filament are favourable to the growth of particles up to larger sizes.
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43
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Matthews M, Morales F, Patas A, Lindinger A, Gateau J, Berti N, Hermelin S, Kasparian J, Richter M, Bredtmann T, Smirnova O, Wolf JP, Ivanov M. Amplification of intense light fields by nearly free electrons. NATURE PHYSICS 2018; 14:695-700. [PMID: 30079094 PMCID: PMC6071854 DOI: 10.1038/s41567-018-0105-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 03/07/2018] [Indexed: 06/07/2023]
Abstract
Light can be used to modify and control properties of media, as in the case of electromagnetically induced transparency or, more recently, for the generation of slow light or bright coherent XUV and X-ray radiation. Particularly unusual states of matter can be created by light fields with strengths comparable to the Coulomb field that binds valence electrons in atoms, leading to nearly-free electrons oscillating in the laser field and yet still loosely bound to the core [1,2]. These are known as Kramers-Henneberger states [3], a specific example of laser-dressed states [2]. Here, we demonstrate that these states arise not only in isolated atoms [4,5], but also in rare gases, at and above atmospheric pressure, where they can act as a gain medium during laser filamentation. Using shaped laser pulses, gain in these states is achieved within just a few cycles of the guided field. The corresponding lasing emission is a signature of population inversion in these states and of their stability against ionization. Our work demonstrates that these unusual states of neutral atoms can be exploited to create a general ultrafast gain mechanism during laser filamentation.
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Affiliation(s)
- Mary Matthews
- GAP, University of Geneva, 22 chemin de Pinchat, 1211 Geneva 4, Switzerland
| | - Felipe Morales
- Max Born Institute, Max Born Strasse 2a, 12489 Berlin, Germany
| | - Alexander Patas
- Inst. Fur Exp. Physik, Freie Universitat Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Albrecht Lindinger
- Inst. Fur Exp. Physik, Freie Universitat Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Julien Gateau
- GAP, University of Geneva, 22 chemin de Pinchat, 1211 Geneva 4, Switzerland
| | - Nicolas Berti
- GAP, University of Geneva, 22 chemin de Pinchat, 1211 Geneva 4, Switzerland
| | - Sylvain Hermelin
- GAP, University of Geneva, 22 chemin de Pinchat, 1211 Geneva 4, Switzerland
| | - Jerome Kasparian
- GAP, University of Geneva, 22 chemin de Pinchat, 1211 Geneva 4, Switzerland
| | - Maria Richter
- Departamento de Quimica, Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Timm Bredtmann
- Max Born Institute, Max Born Strasse 2a, 12489 Berlin, Germany
| | - Olga Smirnova
- Max Born Institute, Max Born Strasse 2a, 12489 Berlin, Germany
| | - Jean-Pierre Wolf
- GAP, University of Geneva, 22 chemin de Pinchat, 1211 Geneva 4, Switzerland
| | - Misha Ivanov
- Max Born Institute, Max Born Strasse 2a, 12489 Berlin, Germany
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Xu B, Jiang S, Yao J, Chen J, Liu Z, Chu W, Wan Y, Zhang F, Qiao L, Lu R, Cheng Y, Xu Z. Free-space Ν2+ lasers generated in strong laser fields: the role of molecular vibration. OPTICS EXPRESS 2018; 26:13331-13339. [PMID: 29801358 DOI: 10.1364/oe.26.013331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 05/03/2018] [Indexed: 06/08/2023]
Abstract
We investigate free-space lasing actions from molecular nitrogen ions (N2+) at the wavelengths of ~391 nm and ~428 nm. Our results show that pronounced gain can be measured at either 391 nm or 428 nm laser wavelength with a pump laser centered at 800 nm wavelength, whereas the gain at 391 nm laser wavelength completely disappears when the wavelength of the pump laser is tuned to 1500 nm. Our theoretical analysis reveals that the different gain behaviors can be attributed to the vibrational distribution of populations in X2Σg+(v=0) and X2Σg+(v=1) states as the N2+ ions are generated by photoionization in the laser fields, giving rise to more robust (i.e., less sensitive to the pump laser wavelength) population inversion for generating the 428 nm laser.
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45
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Britton M, Laferrière P, Ko DH, Li Z, Kong F, Brown G, Naumov A, Zhang C, Arissian L, Corkum PB. Testing the Role of Recollision in N_{2}^{+} Air Lasing. PHYSICAL REVIEW LETTERS 2018; 120:133208. [PMID: 29694197 DOI: 10.1103/physrevlett.120.133208] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 01/20/2018] [Indexed: 06/08/2023]
Abstract
It has been known for many years that during filamentation of femtosecond light pulses in air, gain is observed on the B to X transition in N_{2}^{+}. While the gain mechanism remains unclear, it has been proposed that recollision, a process that is fundamental to much of strong field science, is critical for establishing gain. We probe this hypothesis by directly comparing the influence of the ellipticity of the pump light on gain in air filaments. Then, we decouple filamentation from gain by measuring the gain in a thin gas jet that we also use for high harmonic generation. The latter allows us to compare the dependence of the gain on the ellipticity of the pump with the dependence of the high harmonic signal on the ellipticity of the fundamental. We find that gain and harmonic generation have very different behavior in both filaments and in the jet. In fact, in a jet we even measure gain with circular polarization. Thus, we establish that recollision does not play a significant role in creating the inversion.
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Affiliation(s)
| | | | - Dong Hyuk Ko
- University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
| | - Zhengyan Li
- University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
| | - Fanqi Kong
- University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
| | - Graham Brown
- University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
| | - Andrei Naumov
- National Research Council of Canada, Ottawa K1A 0R6, Ontario, Canada
| | - Chunmei Zhang
- University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
| | - Ladan Arissian
- University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
- National Research Council of Canada, Ottawa K1A 0R6, Ontario, Canada
- University of New Mexico, Albuquerque 87131, New Mexico, USA
| | - P B Corkum
- University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
- National Research Council of Canada, Ottawa K1A 0R6, Ontario, Canada
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Wolf JP. Short-pulse lasers for weather control. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:026001. [PMID: 28783040 DOI: 10.1088/1361-6633/aa8488] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Filamentation of ultra-short TW-class lasers recently opened new perspectives in atmospheric research. Laser filaments are self-sustained light structures of 0.1-1 mm in diameter, spanning over hundreds of meters in length, and producing a low density plasma (1015-1017 cm-3) along their path. They stem from the dynamic balance between Kerr self-focusing and defocusing by the self-generated plasma and/or non-linear polarization saturation. While non-linearly propagating in air, these filamentary structures produce a coherent supercontinuum (from 230 nm to 4 µm, for a 800 nm laser wavelength) by self-phase modulation (SPM), which can be used for remote 3D-monitoring of atmospheric components by Lidar (Light Detection and Ranging). However, due to their high intensity (1013-1014 W cm-2), they also modify the chemical composition of the air via photo-ionization and photo-dissociation of the molecules and aerosols present in the laser path. These unique properties were recently exploited for investigating the capability of modulating some key atmospheric processes, like lightning from thunderclouds, water vapor condensation, fog formation and dissipation, and light scattering (albedo) from high altitude clouds for radiative forcing management. Here we review recent spectacular advances in this context, achieved both in the laboratory and in the field, reveal their underlying mechanisms, and discuss the applicability of using these new non-linear photonic catalysts for real scale weather control.
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Affiliation(s)
- J P Wolf
- Department of Applied Physics (GAP), University of Geneva, 1211 Geneva 4, Switzerland
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47
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Liu Y, Ding P, Ibrakovic N, Bengtsson S, Chen S, Danylo R, Simpson ER, Larsen EW, Zhang X, Fan Z, Houard A, Mauritsson J, L'Huillier A, Arnold CL, Zhuang S, Tikhonchuk V, Mysyrowicz A. Unexpected Sensitivity of Nitrogen Ions Superradiant Emission on Pump Laser Wavelength and Duration. PHYSICAL REVIEW LETTERS 2017; 119:203205. [PMID: 29219339 DOI: 10.1103/physrevlett.119.203205] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Indexed: 06/07/2023]
Abstract
Nitrogen molecules in ambient air exposed to an intense near-infrared femtosecond laser pulse give rise to cavity-free superradiant emission at 391.4 and 427.8 nm. An unexpected pulse duration-dependent cyclic variation of the superradiance intensity is observed when the central wavelength of the femtosecond pump laser pulse is finely tuned between 780 and 820 nm, and no signal occurs at the resonant wavelength of 782.8 nm (2ω_{782.8 nm}=ω_{391.4 nm}). On the basis of a semiclassical recollision model, we show that an interference of dipolar moments of excited ions created by electron recollisions explains this behavior.
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Affiliation(s)
- Yi Liu
- Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, 516, Jungong Road, 200093 Shanghai, China
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 Boulevard des Maréchaux, 91762 Palaiseau cedex, France
| | - Pengji Ding
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 Boulevard des Maréchaux, 91762 Palaiseau cedex, France
- Department of Physics, Lund University, SE-22100 Lund, Sweden
| | - Neven Ibrakovic
- Department of Physics, Lund University, SE-22100 Lund, Sweden
| | | | - Shihua Chen
- Department of Physics, Southeast University, 211189, Nanjing, China
| | - Rostyslav Danylo
- Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, 516, Jungong Road, 200093 Shanghai, China
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 Boulevard des Maréchaux, 91762 Palaiseau cedex, France
| | - Emma R Simpson
- Department of Physics, Lund University, SE-22100 Lund, Sweden
| | - Esben W Larsen
- Department of Physics, Lund University, SE-22100 Lund, Sweden
| | - Xiang Zhang
- Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, 516, Jungong Road, 200093 Shanghai, China
| | - Zhengquan Fan
- Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, 516, Jungong Road, 200093 Shanghai, China
| | - Aurélien Houard
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 Boulevard des Maréchaux, 91762 Palaiseau cedex, France
| | | | - Anne L'Huillier
- Department of Physics, Lund University, SE-22100 Lund, Sweden
| | - Cord L Arnold
- Department of Physics, Lund University, SE-22100 Lund, Sweden
| | - Songlin Zhuang
- Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, 516, Jungong Road, 200093 Shanghai, China
| | - Vladimir Tikhonchuk
- Centre Lasers Intenses et Applications, Université de Bordeaux, CEA, CNRS, Talence 33405, France
| | - André Mysyrowicz
- Laboratoire d'Optique Appliquée, ENSTA ParisTech, CNRS, Ecole polytechnique, Université Paris-Saclay, 828 Boulevard des Maréchaux, 91762 Palaiseau cedex, France
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Cheng Q, Xie X, Yuan Z, Zhong X, Liu Y, Gong Q, Wu C. Dissociative Ionization of Argon Dimer by Intense Femtosecond Laser Pulses. J Phys Chem A 2017; 121:3891-3897. [PMID: 28470067 DOI: 10.1021/acs.jpca.7b02044] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We experimentally and theoretically studied dissociative ionization of argon dimer driven by intense femtosecond laser pulses. In the experiment, we measured the ion yield and the angular distribution of fragmental ions generated from the dissociative ionization channels of (1,1) (Ar22+ → Ar+ + Ar+) and (2,1) (Ar23+ → Ar2+ + Ar+) using a cold target recoil ion momentum spectroscopy. The channel ratio of (2,1)/(1,1) is 4.5-7.5 times of the yield ratio of double ionization to single ionization of argon monomer depending on the laser intensity. The measurement verified that the ionization of Ar+ is greatly enhanced if there exists a neighboring Ar+ separated by a critical distance. In addition, the fragmental ions exhibit an anisotropic angular distribution with the peak along the laser polarization direction and the full width at half maximum becomes broader with increasing laser intensity. Using a full three-dimensional classical ensemble model, we calculated the angle-dependent multiple ionization probability of argon dimer in intense laser fields. The results show that the experimentally observed anisotropic angular distribution of fragmental ions can be attributed to the angle-dependent enhanced ionization of the argon dimer in intense laser fields.
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Affiliation(s)
- Qian Cheng
- State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, School of Physics, Peking University , Beijing 100871, China
| | - Xiguo Xie
- State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, School of Physics, Peking University , Beijing 100871, China
| | - Zongqiang Yuan
- Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, China Academy of Engineering Physics , Mianyang 621900, China
| | - Xunqi Zhong
- State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, School of Physics, Peking University , Beijing 100871, China
| | - Yunquan Liu
- State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, School of Physics, Peking University , Beijing 100871, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University , Taiyuan, Shanxi 030006, China
| | - Qihuang Gong
- State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, School of Physics, Peking University , Beijing 100871, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University , Taiyuan, Shanxi 030006, China
| | - Chengyin Wu
- State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, School of Physics, Peking University , Beijing 100871, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University , Taiyuan, Shanxi 030006, China
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Lei M, Wu C, Zhang A, Gong Q, Jiang H. Population inversion in the rotational levels of the superradiant N 2 + pumped by femtosecond laser pulses. OPTICS EXPRESS 2017; 25:4535-4541. [PMID: 28241656 DOI: 10.1364/oe.25.004535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Nitrogen molecular ions (N2 +) in air plasma pumped by femtosecond laser pulses give rise to superradiant emission at 391.4 nm in the presence of an external seed pulse at proper wavelength. Due to the transient alignment of the nitrogen molecular ions, the superradiance signal presents a strong modulation as a function of the temporal delay between the pump and the seed pulses. Through Fourier transformation with high frequency resolution, we distinguished the contribution of the finely separated rotation levels of the upper and lower states. It was found that the population density of certain rotational levels in the upper state is higher than that in the lower one, indicating that population inversion of the rotation levels of the two involved states is a key enabling factor for this superradiant emission.
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