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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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Zeng T, Gui Y, Yi Y, Li N, Zhang Z, Guo J, Shang B, Guo L. A Simulation of Air Lasing Seeded by an External Wave in a Femtosecond Laser Filament. SENSORS (BASEL, SWITZERLAND) 2023; 23:8364. [PMID: 37896458 PMCID: PMC10611277 DOI: 10.3390/s23208364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/27/2023] [Accepted: 09/29/2023] [Indexed: 10/29/2023]
Abstract
Air lasers induced by femtosecond laser filaments play an important role in remote sensing applications. Few studies have been dedicated to the spatial distribution of external-seeded air laser radiation in the laser filament based on the numerical simulation method, which can pave the way to understanding the mechanism of the external-seeded air lasing process during filamentation. In this study, numerical simulations of the propagation of an air laser seeded by an external plane wave with a wavelength of 391 nm during femtosecond laser filamentation were performed. The results indicated that the air laser's beam intensity distribution varies from a ring pattern to a donut pattern when the filament length and nitrogen ion density are raised as a result of the defocusing and lasing effects of the filament plasma. Here, the ring pattern is formed by several thin rings, while the donut pattern refers to a notably thicker, ring-like structure. In addition, it has been demonstrated that the air laser's beam power would increase exponentially versus the filament length and the nitrogen ion density. The knowledge about the angular distribution of air lasing could be important for optimizing the detection geometry of the LIDAR setup, including the view angle and the size of the collecting optical component.
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Affiliation(s)
- Tao Zeng
- Chongqing Key Laboratory of Micro & Nano Structure Optoeletronics, School of Physical Science and Technology, Southwest University, Chongqing 400715, China; (T.Z.)
| | - Ya Gui
- Chongqing Vocational College of Transportation, Chongqing 402247, China
| | - Yuliang Yi
- Chongqing Key Laboratory of Micro & Nano Structure Optoeletronics, School of Physical Science and Technology, Southwest University, Chongqing 400715, China; (T.Z.)
| | - Nan Li
- Chongqing Key Laboratory of Micro & Nano Structure Optoeletronics, School of Physical Science and Technology, Southwest University, Chongqing 400715, China; (T.Z.)
| | - Zhi Zhang
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Institute of Modern Optics, Nankai University, Tianjin 300350, China
| | - Jiewei Guo
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Institute of Modern Optics, Nankai University, Tianjin 300350, China
| | - Binpeng Shang
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Institute of Modern Optics, Nankai University, Tianjin 300350, China
| | - Lanjun Guo
- Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Institute of Modern Optics, Nankai University, Tianjin 300350, China
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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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Pan S, Zhang Z, Xu L, Zhang W, Lu P, Ji Q, Lin K, Zhou L, Lu C, Ni H, Ruiz C, Ueda K, He F, Wu J. Manipulating Parallel and Perpendicular Multiphoton Transitions in H_{2} Molecules. PHYSICAL REVIEW LETTERS 2023; 130:143203. [PMID: 37084425 DOI: 10.1103/physrevlett.130.143203] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 03/08/2023] [Accepted: 03/16/2023] [Indexed: 05/03/2023]
Abstract
We demonstrate that dissociative ionization of H_{2} can be fully manipulated in an angle-time-resolved fashion, employing a polarization-skewed (PS) laser pulse in which the polarization vector rotates. The leading and falling edges of the PS laser pulse, characterized by unfolded field polarization, trigger, sequentially, parallel and perpendicular transitions of stretching H_{2} molecules, respectively. These transitions result in counterintuitive proton ejections that deviate significantly from the laser polarization directions. Our findings demonstrate that the reaction pathways can be controlled through fine-tuning the time-dependent polarization of the PS laser pulse. The experimental results are well reproduced using an intuitive wave-packet surface propagation simulation method. This research highlights the potential of PS laser pulses as powerful tweezers to resolve and manipulate complex laser-molecule interactions.
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Affiliation(s)
- Shengzhe Pan
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Zhaohan Zhang
- Key Laboratory for Laser Plasmas (Ministry of Education) and School of Physics and Astronomy, Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240, China
| | - Liang Xu
- Key Laboratory for Laser Plasmas (Ministry of Education) and School of Physics and Astronomy, Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240, China
- Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Wenbin Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Peifen Lu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Qinying Ji
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Kang Lin
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Lianrong Zhou
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Chenxu Lu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Hongcheng Ni
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Camilo Ruiz
- Instituto Universitario de Física Fundamental y Matemáticas, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca, Spain
| | - Kiyoshi Ueda
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
- Department of Chemistry, Tohoku University, Sendai 980-8578, Japan
| | - Feng He
- Key Laboratory for Laser Plasmas (Ministry of Education) and School of Physics and Astronomy, Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Ultra-intense Laser Science, Shanghai 201800, China
| | - Jian Wu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
- CAS Center for Excellence in Ultra-intense Laser Science, Shanghai 201800, China
- Chongqing Key Laboratory of Precision Optics, Chongqing Institute of East China Normal University, Chongqing 401121, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
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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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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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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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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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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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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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