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Mazza F, Stutvoet A, Castellanos L, Kliukin D, Bohlin A. Coherent Raman spectroscopy on hydrogen with in-situ generation, in-situ use, and in-situ referencing of the ultrabroadband excitation. OPTICS EXPRESS 2022; 30:35232-35245. [PMID: 36258479 DOI: 10.1364/oe.465817] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 08/25/2022] [Indexed: 06/16/2023]
Abstract
Time-resolved spectroscopy can provide valuable insights in hydrogen chemistry, with applications ranging from fundamental physics to the use of hydrogen as a commercial fuel. This work represents the first-ever demonstration of in-situ femtosecond laser-induced filamentation to generate a compressed supercontinuum behind a thick optical window, and its in-situ use to perform femtosecond/picosecond coherent Raman spectroscopy (CRS) on molecular hydrogen (H2). The ultrabroadband coherent excitation of Raman active molecules in measurement scenarios within an enclosed space has been hindered thus far by the window material imparting temporal stretch to the pulse. We overcome this challenge and present the simultaneous single-shot detection of the rotational H2 and the non-resonant CRS spectra in a laminar H2/air diffusion flame. Implementing an in-situ referencing protocol, the non-resonant spectrum measures the spectral phase of the supercontinuum pulse and maps the efficiency of the ultrabroadband coherent excitation achieved behind the window. This approach provides a straightforward path for the implementation of ultrabroadband H2 CRS in enclosed environment such as next-generation hydrogen combustors and reforming reactors.
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2
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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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Chang J, Li D, Xu L, Zhang L, Xi T, Hao Z. Elongation of filamentation and enhancement of supercontinuum generation by a preformed air density hole. OPTICS EXPRESS 2022; 30:16987-16995. [PMID: 36221531 DOI: 10.1364/oe.458128] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 04/23/2022] [Indexed: 06/16/2023]
Abstract
The filamentation of the femtosecond laser pulse in air with a preformed density hole is studied numerically. The result shows that density-hole-induced defocusing effect can relieve the self-focusing of the pulse, and by changing the length of the density hole and relative delay time, the filamentation length, intensity, spectral energy density and broaden region can be effectively controlled. When a short density hole with millisecond delay time is introduced, a significant elongation of the filamentation and enhancement of supercontinuum intensity can be obtained. This study provides a new method to control filamentation by pulse sequence.
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Edwards MR, Mikhailova JM. The X-Ray Emission Effectiveness of Plasma Mirrors: Reexamining Power-Law Scaling for Relativistic High-Order Harmonic Generation. Sci Rep 2020; 10:5154. [PMID: 32198482 PMCID: PMC7083899 DOI: 10.1038/s41598-020-61255-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 02/19/2020] [Indexed: 11/20/2022] Open
Abstract
Ultrashort pulsed lasers provide uniquely detailed access to the ultrafast dynamics of physical, chemical, and biological systems, but only a handful of wavelengths are directly produced by solid-state lasers, necessitating efficient high-power frequency conversion. Relativistic plasma mirrors generate broadband power-law spectra, that may span the gap between petawatt-class infrared laser facilities and x-ray free-electron lasers; despite substantial theoretical work the ultimate efficiency of this relativistic high-order-harmonic generation remains unclear. We show that the coherent radiation emitted by plasma mirrors follows a power-law distribution of energy over frequency with an exponent that, even in the ultrarelativistic limit, strongly depends on the ratio of laser intensity to plasma density and exceeds the frequently quoted value of -8/3 over a wide range of parameters. The coherent synchrotron emission model, when adequately corrected for the finite width of emitting electron bunches, is not just valid for p-polarized light and thin foil targets, but generally describes relativistic harmonic generation, including at normal incidence and with finite-gradient plasmas. Our numerical results support the ω-4/3 scaling of the synchrotron emission model as a limiting efficiency of the process under most conditions. The highest frequencies that can be generated with this scaling are usually restricted by the width of the emitting electron bunch rather than the Lorentz factor of the fastest electrons. The theoretical scaling relations developed here suggest, for example, that with a 20-PW 800-nm driving laser, 1 TW/harmonic can be produced for 1-keV photons.
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Affiliation(s)
- Matthew R Edwards
- Princeton University, Department of Mechanical and Aerospace Engineering, Princeton, New Jersey, 08544, USA.
| | - Julia M Mikhailova
- Princeton University, Department of Mechanical and Aerospace Engineering, Princeton, New Jersey, 08544, USA.
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Supercontinuum generation by co-filamentation of two color femtosecond laser pulses. Sci Rep 2019; 9:9011. [PMID: 31227741 PMCID: PMC6588607 DOI: 10.1038/s41598-019-45357-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 06/05/2019] [Indexed: 11/08/2022] Open
Abstract
In this paper, we experimentally investigate supercontinuum generation via collinear two-color filamentation in sapphire crystal, by launching two femtosecond pulses at fundamental (1030 nm) and second harmonic (515 nm) wavelengths from an amplified Yb:KGW laser. By changing the time delay between the incident pulses, we observe dramatic changes in the supercontinuum spectrum, transmitted energy, position of the nonlinear focus and intensity distribution along the filamentinduced luminescence traces. In particular, we show that at some delays the two pump wavelengths can assist each other in generating supercontinuum, whilst at other delays large portions of the supercontinuum spectrum are completely extinguished. The transition between supercontinuum generation and its extinction occurs within a very short (20 fs) span of the delay times, despite the fact that the pump pulses are 220 fs long. We propose that the observed non-trivial spectral dynamics can be interpreted by a mechanism, where co-propagating two pump pulses perturb the nonlinear refractive properties of the medium via Kerr effect and generation of free electron plasma thereby affecting pulse splitting and pulse front steepening, which are the key players in the process of supercontinuum generation in a normally dispersive medium.
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Kostin VA, Vvedenskii NV. Generation of Few- and Subcycle Radiation in Midinfrared-to-Deep-Ultraviolet Range During Plasma Production by Multicolor Femtosecond Pulses. PHYSICAL REVIEW LETTERS 2018; 120:065002. [PMID: 29481218 DOI: 10.1103/physrevlett.120.065002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Indexed: 06/08/2023]
Abstract
Our closed-form analytical formulas and numerical calculations show that the plasma production by a two-color (or, more generally, multicolor) femtosecond pulse leads to generation of strong few- and subcycle radiation. The spectral composition of the radiation is defined by the numerous combination frequencies of the ionizing pulse. The radiation duration is equal to the ionization duration, which is much shorter than the multicolor pump. The phenomenon opens a new direct (without additional compression) way to create tunable sources of extremely short pulses with smooth envelopes and spectra in a broad range stretching from the midinfrared to the deep ultraviolet.
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Affiliation(s)
- V A Kostin
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia
- University of Nizhny Novgorod, Nizhny Novgorod 603950, Russia
| | - N V Vvedenskii
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia
- University of Nizhny Novgorod, Nizhny Novgorod 603950, Russia
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Shanor C, Ensley T, Hagan DJ, Van Stryland EW, Wright EM, Kolesik M. Numerical investigation of enhanced femtosecond supercontinuum via a weak seed in noble gases. OPTICS EXPRESS 2016; 24:15110-15119. [PMID: 27410662 DOI: 10.1364/oe.24.015110] [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
Numerical simulations are employed to elucidate the physics underlying the enhanced femtosecond supercontinuum generation previously observed during optical filamentation in noble gases and in the presence of a weak seed pulse. Simulations based on the metastable electronic state approach are shown not only to capture the qualitative features of the experiment, but also reveal the relation of the observed enhancement to recent developments in the area of sub-cycle engineering of filaments.
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Rezvani SA, Zhang Q, Hong Z, Lu P. Tunable broadband intense IR pulse generation at non-degenerate wavelengths using group delay compensation in a dual-crystal OPA scheme. OPTICS EXPRESS 2016; 24:11187-11198. [PMID: 27409940 DOI: 10.1364/oe.24.011187] [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
A robust group delay compensated dual-crystal optical parametric amplification (DOPA) scheme is proposed that will be used to prove the positive effect of group delay compensation on a DOPA as predicted by the simulations in the previously published literature. Through simple adjustments, it is also capable of providing 20 fs pulses (theoretically compressible to 12 fs, corresponding to sub-four-cycle for 1300 nm components), broadband IR pulses at non-degenerate wavelengths using short pulse (broadband) pump laser. In our table-top DOPA system, group delay compensation has been realized using a simple optical crystal. Our design provides output power in order of 100 mW. We managed to achieve minimum 20 nm improvement on the bandwidth, compared to single-crystal OPA (SOPA) structure whilst keeping total conversion efficiency above 30%. Adjusting our configuration by optimizing the phase-matching angles of the two BBO crystals, we also have realized a practical scheme that benefitting from group delay compensation can obtain 75 nm bandwidth improvement while keeping the conversion efficiency constant. This achievement will open the doors to the realm of multiple crystals OPA systems and provide a solution to the imposed limitation on the effective lengths of applicable non-linear crystals and hence limited power gain of such broadband OPA systems.
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Yang J, Zeng T, Lin L, Liu W. Beam wandering of femtosecond laser filament in air. OPTICS EXPRESS 2015; 23:25628-25634. [PMID: 26480079 DOI: 10.1364/oe.23.025628] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The spatial wandering of a femtosecond laser filament caused by the filament heating effect in air has been studied. An empirical formula has also been derived from the classical Karman turbulence model, which determines quantitatively the displacement of the beam center as a function of the propagation distance and the effective turbulence structure constant. After fitting the experimental data with this formula, the effective turbulence structure constant has been estimated for a single filament generated in laboratory environment. With this result, one may be able to estimate quantitatively the displacement of a filament over long distance propagation and interpret the practical performance of the experiments assisted by femtosecond laser filamentation, such as remote air lasing, pulse compression, high order harmonic generation (HHG), etc.
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10
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Kida Y, Imasaka T. Generation of intense subcycle optical pulses in a gas. OPTICS EXPRESS 2015; 23:12373-12381. [PMID: 25969322 DOI: 10.1364/oe.23.012373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The generation of intense subcycle laser pulses during the propagation of two-color femtosecond pulses in a gas medium is investigated theoretically and experimentally. Four-wave mixing induced by the laser pulses in a gas medium generates multi-octave laser radiation from the ultraviolet to the infrared, which forms stable subcycle laser pulses after a certain propagation distance in a gas medium with group-velocity dispersion. The intense subcycle laser pulses would allow the coherent control of the waveforms of soft-x-rays generated via high-harmonic generation.
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11
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Horio T, Spesyvtsev R, Suzuki T. Generation of sub-17 fs vacuum ultraviolet pulses at 133 nm using cascaded four-wave mixing through filamentation in Ne. OPTICS LETTERS 2014; 39:6021-6024. [PMID: 25361145 DOI: 10.1364/ol.39.006021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The sixth harmonic (6ω, 133 nm) of a Ti:sapphire laser is generated using cascaded four-wave mixing in filamentation propagation of the fundamental (ω) and the second harmonic (2ω) pulses through Ne gas. The method provides the 6ω pulse energy higher than 5 nJ/pulse at 1 kHz and a pulse duration shorter than 17 fs without dispersion compensation.
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12
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Abstract
Femtosecond laser filamentation occurs as a dynamic balance between the self-focusing and plasma defocusing of a laser pulse to produce ultrashort radiation as brief as a few optical cycles. This unique source has many properties that make it attractive as a nonlinear optical tool for spectroscopy, such as propagation at high intensities over extended distances, self-shortening, white-light generation, and the formation of an underdense plasma. The plasma channel that constitutes a single filament and whose position in space can be controlled by its input parameters can span meters-long distances, whereas multifilamentation of a laser beam can be sustained up to hundreds of meters in the atmosphere. In this review, we briefly summarize the current understanding and use of laser filaments for spectroscopic investigations of molecules. A theoretical framework of filamentation is presented, along with recent experimental evidence supporting the established understanding of filamentation. Investigations carried out on vibrational and rotational spectroscopy, filament-induced breakdown, fluorescence spectroscopy, and backward lasing are discussed.
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Affiliation(s)
- Johanan Odhner
- Department of Chemistry and Center for Advanced Photonics Research, Temple University, Philadelphia, Pennsylvania 19122
| | - Robert Levis
- Department of Chemistry and Center for Advanced Photonics Research, Temple University, Philadelphia, Pennsylvania 19122
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13
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Xu Z, Zhu X, Yu Y, Zhang N, Zhao J. Super-luminescent jet light generated by femtosecond laser pulses. Sci Rep 2014; 4:3892. [PMID: 24463611 PMCID: PMC3902405 DOI: 10.1038/srep03892] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 01/07/2014] [Indexed: 11/09/2022] Open
Abstract
Phenomena of nonlinear light-matter interaction that occur during the propagation of intense ultrashort laser pulses in continuous media have been extensively studied in ultrafast optical science. In this vibrant research field, conversion of the input laser beam into optical filament(s) is commonly encountered. Here, we demonstrate generation of distinctive single or double super-luminescent optical jet beams as a result of strong spatial-temporal nonlinear interaction between focused 50 fs millijoule laser pulses and their induced micro air plasma. Such jet-like optical beams, being slightly divergent and coexisting with severely distorted conical emission of colored speckles, are largely different from optical filaments, and obtainable when the focal lens of proper f-number is slightly tilted or shifted. Once being collimated, the jet beams can propagate over a long distance in air. These beams not only reveal a potentially useful approach to coherent optical wave generation, but also may find applications in remote sensing.
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Affiliation(s)
- Zhijun Xu
- Institute of Modern Optics, Nankai University, Key Laboratory of Optical Information Science and Technology, Education Ministry of China, Tianjin 300071, P. R. China
| | - Xiaonong Zhu
- Institute of Modern Optics, Nankai University, Key Laboratory of Optical Information Science and Technology, Education Ministry of China, Tianjin 300071, P. R. China
| | - Yang Yu
- Institute of Modern Optics, Nankai University, Key Laboratory of Optical Information Science and Technology, Education Ministry of China, Tianjin 300071, P. R. China
| | - Nan Zhang
- Institute of Modern Optics, Nankai University, Key Laboratory of Optical Information Science and Technology, Education Ministry of China, Tianjin 300071, P. R. China
| | - Jiefeng Zhao
- Institute of Modern Optics, Nankai University, Key Laboratory of Optical Information Science and Technology, Education Ministry of China, Tianjin 300071, P. R. China
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14
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Horio T, Spesyvtsev R, Suzuki T. Simultaneous generation of sub-20 fs deep and vacuum ultraviolet pulses in a single filamentation cell and application to time-resolved photoelectron imaging. OPTICS EXPRESS 2013; 21:22423-22428. [PMID: 24104131 DOI: 10.1364/oe.21.022423] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Sub-20 fs pulses of the third, fourth, and fifth harmonics of a Ti:sapphire laser are simultaneously generated using cascaded four-wave mixing in filamentation propagation of the fundamental frequency and the second harmonic pulses in Ne gas. Reflective optics under vacuum are employed after the four-wave mixing to minimize material dispersion of the optical pulses. The cross-correlation between 198 and 159 nm pulses of 18 fs is achieved without dispersion compensation. This new light source is applied to time-resolved photoelectron imaging of carbon disulfide (CS₂).
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15
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Théberge F, Lassonde P, Payeur S, Châteauneuf M, Dubois J, Kieffer JC. Efficient spectral-step expansion of a filamenting laser pulse. OPTICS LETTERS 2013; 38:1576-1578. [PMID: 23632557 DOI: 10.1364/ol.38.001576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report an efficient transfer of 800 nm energy into both the ultraviolet and the far infrared (IR) during the filamentation in air of an appropriately shaped laser pulse. The multiorder enhancement of the IR supercontinuum in the 3-5 μm atmospheric transmission windows was achieved thanks to spectral-step cascaded four-wave mixing occurring within the spectrum of the shaped femtosecond laser pulse. These results also point out the limit of the self-phase modulation model to explain the spectral broadening of a filamenting laser pulse.
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Affiliation(s)
- Francis Théberge
- Defence R&D Canada Valcartier, Québec (Qc), Canada. francis.theberge@drdc‑rddc.gc.ca
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Ni J, Chu W, Jing C, Zhang H, Zeng B, Yao J, Li G, Xie H, Zhang C, Xu H, Chin SL, Cheng Y, Xu Z. Identification of the physical mechanism of generation of coherent N2(+) emissions in air by femtosecond laser excitation. OPTICS EXPRESS 2013; 21:8746-8752. [PMID: 23571963 DOI: 10.1364/oe.21.008746] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Recently, amplification of harmonic-seeded radiation generated through femtosecond laser filamentation in air has been observed, giving rise to coherent emissions at wavelengths corresponding to transitions between different vibrational levels of the electronic B(2)Σ(u)(+) and X(2)Σ(g)(+) states of molecular nitrogen ions [Phys. Rev. A. 84, 051802(R) (2011)]. Here, we carry out systematic investigations on its physical mechanism. Our experimental results do not support the speculation that such excellent coherent emissions could originate from nonlinear optical processes such as four-wave mixing or stimulated Raman scattering, leaving stimulated amplification of harmonic seed due to the population inversion generated in molecular nitrogen ions the most likely mechanism.
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Affiliation(s)
- Jielei Ni
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800, China
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17
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Generation of Phase-Stable Sub-Cycle Mid-Infrared Pulses from Filamentation in Nitrogen. APPLIED SCIENCES-BASEL 2013. [DOI: 10.3390/app3010122] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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18
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Xu S, Sun X, Zeng B, Chu W, Zhao J, Liu W, Cheng Y, Xu Z, Chin SL. Simple method of measuring laser peak intensity inside femtosecond laser filament in air. OPTICS EXPRESS 2012; 20:299-307. [PMID: 22274353 DOI: 10.1364/oe.20.000299] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Measurement of laser intensity inside a femtosecond laser filament is a challenging task. In this work, we suggest a simple way to characterize laser peak intensity inside the filament in air. It is based on the signal ratio measurement of two nitrogen fluorescence lines, namely, 391 nm and 337 nm. Because of distinct excitation mechanisms, the signals of the two fluorescence lines increase with the laser intensity at different orders of nonlinearity. An empirical formula has been deduced according to which laser peak intensity could be simply determined by the fluorescence ratio.
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Affiliation(s)
- Shengqi Xu
- Institute of Modern Optics, Nankai University, Key Laboratory of Optical Information Science and Technology, Ministry of Education, Tianjin, 300071 China
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Daigle JF, Wang TJ, Hosseini S, Yuan S, Roy G, Chin SL. Dynamic behavior of postfilamentation Raman pulses. APPLIED OPTICS 2011; 50:6234-6238. [PMID: 22108881 DOI: 10.1364/ao.50.006234] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report on the postfilamentation behavior of a Stokes pulse created from intense and collimated ultrashort pulses propagating in air. A systematic analysis of the pulse propagation revealed that the redshifted Raman pulse produced during filamentation had a larger divergence than the postfilamentation intense pump pulse. Also, the analysis of the far-field Stokes transverse ring revealed that the intensity in this ionization-free light channel is still sufficiently high to induce stimulated Raman scattering after ionization had ended. This behavior further extends the potential of filamentation to remotely induce third-order nonlinearities.
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Affiliation(s)
- Jean-François Daigle
- Centre d’Optique, Photonique et Laser et Département de physique, de génie physique et d’optique, Université Laval, Québec, Canada.
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20
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Liu XL, Lu X, Liu X, Feng LB, Ma JL, Li YT, Chen LM, Dong QL, Wang WM, Wang ZH, Wei ZY, Sheng ZM, Zhang J. Broadband supercontinuum generation in air using tightly focused femtosecond laser pulses. OPTICS LETTERS 2011; 36:3900-3902. [PMID: 21964135 DOI: 10.1364/ol.36.003900] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Supercontinuum generation in air using tightly focused femtosecond laser pulses was investigated experimentally. Broadband white-light emission covering the whole visible spectral region was generated. Spectral broadening extended only to the blue side of the fundamental frequency due to the phase modulation induced by the strong ionization of air. Numerical simulation was also performed to confirm the spectral broadening mechanism. A constant UV cutoff wavelength close to 400 nm was observed in the supercontinuum spectrum. This phenomenon indicated that intensity clamping still plays a role in tight focusing geometry.
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Affiliation(s)
- Xiao-Long Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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21
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Lassonde P, Théberge F, Payeur S, Châteauneuf M, Dubois J, Kieffer JC. Infrared generation by filamentation in air of a spectrally shaped laser beam. OPTICS EXPRESS 2011; 19:14093-14098. [PMID: 21934771 DOI: 10.1364/oe.19.014093] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We demonstrated the generation of infrared radiation by filamentation of a spectrally shaped femtosecond laser beam. The spectrum is divided in two distinctive parts using an acousto-optic programmable dispersive filter (AOPDF) as a pulse shaper, resulting in two pulses of different colors. One pulse is frequency doubled and the beams are then focused to produce an optical filament. Efficient infrared generation occurred in the filament zone through the four-wave mixing interaction. This in-line setup allowed perfect spatial overlap of the pulses, fine control of the relative delay and the remote control of the infrared spectral distribution through spectral shaping of the initial femtosecond laser beam via the AOPDF.
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Affiliation(s)
- P Lassonde
- Institut National de la Recherche Scientifique Énergie, Matériaux et Télécommunications, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada.
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Ensley TR, Fishman DA, Webster S, Padilha LA, Hagan DJ, Van Stryland EW. Energy and spectral enhancement of femtosecond supercontinuum in a noble gas using a weak seed. OPTICS EXPRESS 2011; 19:757-763. [PMID: 21263616 DOI: 10.1364/oe.19.000757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We experimentally demonstrate that the use of a weak seed pulse of energy less than 0.4% of the pump results in a spectral energy enhancement that spans over 2 octaves and a total energy enhancement of more than 3 times for supercontinua generated by millijoule level femtosecond pulses in Krypton gas. Strong four-wave mixing of the pump-seed pulse interacting in the gas is observed. The spectral irradiance generated from the seeding process is sufficiently high to use white-light continuum as an alternative to conventional tunable sources of radiation for applications such as nonlinear optical spectroscopy.
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Affiliation(s)
- Trenton R Ensley
- College of Optics & Photonics: CREOL & FPCE, University of Central Florida, Orlando, Florida 32816-2700, USA
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23
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Femtosecond laser filamentation for atmospheric sensing. SENSORS 2010; 11:32-53. [PMID: 22346566 PMCID: PMC3274092 DOI: 10.3390/s110100032] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 12/10/2010] [Accepted: 12/13/2010] [Indexed: 12/11/2022]
Abstract
Powerful femtosecond laser pulses propagating in transparent materials result in the formation of self-guided structures called filaments. Such filamentation in air can be controlled to occur at a distance as far as a few kilometers, making it ideally suited for remote sensing of pollutants in the atmosphere. On the one hand, the high intensity inside the filaments can induce the fragmentation of all matters in the path of filaments, resulting in the emission of characteristic fluorescence spectra (fingerprints) from the excited fragments, which can be used for the identification of various substances including chemical and biological species. On the other hand, along with the femtosecond laser filamentation, white-light supercontinuum emission in the infrared to UV range is generated, which can be used as an ideal light source for absorption Lidar. In this paper, we present an overview of recent progress concerning remote sensing of the atmosphere using femtosecond laser filamentation.
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24
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Börzsönyi Á, Heiner Z, Kovács AP, Kalashnikov MP, Osvay K. Measurement of pressure dependent nonlinear refractive index of inert gases. OPTICS EXPRESS 2010; 18:25847-25854. [PMID: 21164930 DOI: 10.1364/oe.18.025847] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The propagation of high intensity laser beams is excessively affected by optical nonlinear effects, thereby the knowledge of the nonlinear refractive indices of the beam guiding media is indispensable in the design of laser systems and experiments. Apart from undesired self-focusing, several areas of modern laser spectroscopy can utilize optical nonlinearity, from LiDAR measurements to filamentation. In this paper we report on a direct measurement of pressure dependent nonlinear refractive index of Ar, N2, Ne, Xe, and air between 0.05 mbar and 1 bar, based on the powerful technique called spectrally and spatially resolved interferometry. In this way the total value of nonlinear refractive index is measured, that is the sum of all elementary phenomena contributing to the intensity dependent refractivity of the gases.
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Affiliation(s)
- Á Börzsönyi
- Dept of Optics and Quantum Electronics, University of Szeged, PO Box 406, Szeged 6701, Hungary
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25
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Ghotbi M, Beutler M, Noack F. Generation of 2.5 μJ vacuum ultraviolet pulses with sub-50 fs duration by noncollinear four-wave mixing in argon. OPTICS LETTERS 2010; 35:3492-3494. [PMID: 20967110 DOI: 10.1364/ol.35.003492] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Generation of sub-50fs vacuum UV pulses with more than 2.5μJ energy at a 1kHz repetition rate is reported. The pulses at 160nm are produced using noncollinear difference-frequency four-wave mixing between the fundamental and third harmonics of an amplified Ti:sapphire laser in argon. While the pulse duration is maintained by increasing the phase-matching pressure, noncollinear interaction improves the conversion efficiency by 1 order of magnitude in comparison with the previous results in collinear geometry.
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Affiliation(s)
- M Ghotbi
- Max-Born-Institute for Nonlinear Optics and Ultrafast Spectroscopy, 2A Max-Born-Strasse, D-12489 Berlin, Germany. mghotbi@mbi‑berlin.de
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26
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Zuo P, Fuji T, Suzuki T. Spectral phase transfer to ultrashort UV pulses through four-wave mixing. OPTICS EXPRESS 2010; 18:16183-16192. [PMID: 20721004 DOI: 10.1364/oe.18.016183] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Transfer of spectral phase from near infrared ultrashort pulses to deep ultraviolet (UV) sub-30-fs pulses through four-wave mixing process is demonstrated. Micro joule UV pulses at 237 nm were generated by nonlinear mixing of second harmonic pulses of Ti:sapphire laser output and near infrared pulses from a noncollinear optical parametric amplifier. Chirp of the near infrared pulse was transferred to the UV pulse with the opposite sign. A positively chirped near infrared pulse was used for generating a negatively chirped UV pulse, which was compressed down to 25 fs by a magnesium fluoride window.
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Affiliation(s)
- P Zuo
- Chemical Dynamics Laboratory, RIKEN Advanced Science Institute, Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
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27
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Beutler M, Ghotbi M, Noack F, Hertel IV. Generation of sub-50-fs vacuum ultraviolet pulses by four-wave mixing in argon. OPTICS LETTERS 2010; 35:1491-1493. [PMID: 20436613 DOI: 10.1364/ol.35.001491] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report on the generation of femtosecond pulses at 160 nm with energies up to 240 nJ at 1 kHz repetition rate and sub-50-fs pulse duration. This pulse energy is a 1-order-of-magnitude improvement compared with previous sub-100-fs sources in this wavelength range. The pulses are generated by four-wave difference-frequency mixing process between the fundamental of a Ti:sapphire laser and its third harmonic in argon. Pulse duration measurements are achieved by pump-probe ionization of Xe gas providing the cross correlation between the fifth harmonic and the fundamental.
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Affiliation(s)
- Marcus Beutler
- Max-Born-Institute for Nonlinear Optics and Ultrafast Spectroscopy, Max-Born-Strasse 2a, 12489 Berlin, Germany.
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28
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Liu J, Kobayashi T. Generation and amplification of tunable multicolored femtosecond laser pulses by using cascaded four-wave mixing in transparent bulk media. SENSORS (BASEL, SWITZERLAND) 2010; 10:4296-341. [PMID: 22399882 PMCID: PMC3292121 DOI: 10.3390/s100504296] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 04/11/2010] [Accepted: 04/16/2010] [Indexed: 11/16/2022]
Abstract
We have reviewed the generation and amplification of wavelength-tunable multicolored femtosecond laser pulses using cascaded four-wave mixing (CFWM) in transparent bulk media, mainly concentrating on our recent work. Theoretical analysis and calculations based on the phase-matching condition could explain well the process semi-quantitatively. The experimental studies showed: (1) as many as fifteen spectral up-shifted and two spectral down-shifted sidebands were obtained simultaneously with spectral bandwidth broader than 1.8 octaves from near ultraviolet (360 nm) to near infrared (1.2 μm); (2) the obtained sidebands were spatially separated well and had extremely high beam quality with M(2) factor better than 1.1; (3) the wavelengths of the generated multicolor sidebands could be conveniently tuned by changing the crossing angle or simply replacing with different media; (4) as short as 15-fs negatively chirped or nearly transform limited 20-fs multicolored femtosecond pulses were obtained when one of the two input beams was negatively chirped and the other was positively chirped; (5) the pulse energy of the sideband can reach a μJ level with power stability better than 1% RMS; (6) broadband two-dimensional (2-D) multicolored arrays with more than ten periodic columns and more than ten rows were generated in a sapphire plate; (7) the obtained sidebands could be simultaneously spectra broadened and power amplified in another bulk medium by using cross-phase modulation (XPM) in conjunction with four-wave optical parametric amplification (FOPA). The characterization showed that this is interesting and the CFWM sidebands generated by this novel method have good enough qualities in terms of power stability, beam quality, and temporal features suited to various experiments such as ultrafast multicolor time-resolved spectroscopy and multicolor-excitation nonlinear microscopy.
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Affiliation(s)
- Jun Liu
- Department of Applied Physics and Chemistry and Institute for Laser Science, University of Electro-Communications, Chofugaoka 1-5-1, Chofu, Tokyo 182-8585, Japan; E-Mail:
- International Cooperative Research Project (ICORP), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Takayoshi Kobayashi
- Department of Applied Physics and Chemistry and Institute for Laser Science, University of Electro-Communications, Chofugaoka 1-5-1, Chofu, Tokyo 182-8585, Japan; E-Mail:
- International Cooperative Research Project (ICORP), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
- Department of Electrophysics, National Chiao Tung University, 1001 Ta Hsueh Rd. Hsinchu 300, Taiwan
- Institute of Laser Engineering, Osaka University, Yamadakami 2-6, Suita, Osaka 565-0871, Japan
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29
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Wang Z, Liu J, Li R, Xu Z. Wavefront control to generate ultraviolet supercontinuum by filamentation of few-cycle laser pulses in argon. OPTICS LETTERS 2010; 35:163-165. [PMID: 20081955 DOI: 10.1364/ol.35.000163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We numerically demonstrated the filamentation dynamics of a 6 fs, 800 nm pulse focused in argon at atmospheric pressure by a zone plate and a concave mirror. In comparison with a concave mirror, the zone plate has a frequency-dependent focal length and can be used to control the wavefront of the laser beam in the frequency domain. A separate supercontinuum in the ultraviolet region extending from 250 to 300 nm and peaked at ~280 nm can be generated by using a proper zone plate.
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Affiliation(s)
- Zhanxin Wang
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800, China
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30
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Yang X, Wu J, Peng Y, Tong Y, Lu P, Ding L, Xu Z, Zeng H. Plasma waveguide array induced by filament interaction. OPTICS LETTERS 2009; 34:3806-3808. [PMID: 20016620 DOI: 10.1364/ol.34.003806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We demonstrate that interference-assisted coalescence of two noncollinearly overlapped filaments creates a wavelength-scale periodic plasma density modulation to guide the input pulses equivalently as a photonic crystal plasma waveguide. The periodic self-channeling is evidenced by the direct observation of the filament coalescence, which reveals wavelength-scale spatial widths and periodicity dependent on the crossing angles and intensity ratios between the incident filaments.
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Affiliation(s)
- Xuan Yang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
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31
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Liu J, Kobayashi T. Generation of sub-20-fs multicolor laser pulses using cascaded four-wave mixing with chirped incident pulses. OPTICS LETTERS 2009; 34:2402-2404. [PMID: 19684796 DOI: 10.1364/ol.34.002402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Negatively chirped or nearly transform-limited output pulses can be obtained in a four-wave mixing process when one of the pump beams is negatively chirped and the other is positively chirped. Nearly transform-limited 16 fs multicolor laser pulses are obtained in a fused-silica glass plate using this method. The resulting frequency shifts and compressed multicolor sidebands are continuously tunable in wavelength by varying the crossing angle between the two input beams. Sub-10-fs multicolor pulses should be possible obtained using this method in the future.
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Affiliation(s)
- Jun Liu
- Department of Applied Physics and Chemistry and Institute for Laser Science,University of Electro-Communications, Chofugaoka 1-5-1, Chofu, Tokyo 182-8585 Japan.
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32
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Wang Z, Liu J, Li R, Xu Z. Supercontinuum generation and pulse compression from gas filamentation of femtosecond laser pulses with different durations. OPTICS EXPRESS 2009; 17:13841-13850. [PMID: 19654790 DOI: 10.1364/oe.17.013841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Self-compression and spectral supercontinuum (SC) generated by filamentation of femtosecond laser pulses with duration from 45 fs down to 6 fs in argon gas have been numerically investigated. A 45-fs pulse can be self-compressed into a few-cycle pulse with duration of 12 fs at the post-filamentation region. By properly employing a high-pass filter to select the broadening high-frequency spectra which are almost in phase, the pulse can be further shortened to about 7 fs. By contrast, a 6-fs pulse cannot be further self-compressed into a shorter pulse by filamentation although it can generate much broader SC extending from 200 nm to 1300 nm. It is also found that a separate and strong SC in the ultraviolet (UV) region extending from 220 nm to 300 nm and peaked at about 255 nm can be generated at proper propagation distances, which corresponds to a pulse with duration of about 5 fs.
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Affiliation(s)
- Zhanxin Wang
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
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33
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Shwa D, Eisenmann S, Marcus G, Zigler A. Using the self-filtering property of a femtosecond filament to improve second harmonic generation. OPTICS EXPRESS 2009; 17:6451-6456. [PMID: 19365469 DOI: 10.1364/oe.17.006451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In this paper we demonstrate the use of NIR femtosecond filament for improving the generation of second harmonic using a type I BBO crystal. Using this method the beam propagation factor (M(2)) of the second harmonic was improved significantly; which led to enhancement of the attainable SH intensity by up to two orders of magnitude. This method can be beneficial for applications demanding high intensities, small spot size or long interaction lengths.
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Affiliation(s)
- David Shwa
- Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel
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34
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Liu J, Kobayashi T. Wavelength-tunable, multicolored femtosecond-laser pulse generation in fused-silica glass. OPTICS LETTERS 2009; 34:1066-1068. [PMID: 19340221 DOI: 10.1364/ol.34.001066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Wavelength-tunable multicolored femtosecond laser pulses were generated simultaneously through cascade four-wave mixing in a fused-silica glass plate using two crossing femtosecond laser beams. The wavelength of the sidebands can be continuously tuned from UV to IR. The pulse duration, spatial mode, spectrum, and energy stability of the sidebands indicated that they were good enough for various multicolor femtosecond laser experiments. As many as 15 spectral upshifted pulses and 2 spectral downshifted pulses were obtained with a spectral bandwidth broader than 1.8 octaves.
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Affiliation(s)
- Jun Liu
- Department of Applied Physics and Chemistry, Institute for Laser Science, University of Electro-Communications, Tokyo, Japan.
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35
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Liu J, Kobayashi T. Generation of microJ-level multicolored femtosecond laser pulses using cascaded four-wave mixing. OPTICS EXPRESS 2009; 17:4984-4990. [PMID: 19333258 DOI: 10.1364/oe.17.004984] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Multicolor femtosecond pulses were simultaneously obtained by a cascaded FWM process in fused silica glass. The sideband spectra were tunable by changing the crossing angle of the two input beams. Frequency up-shift and down-shift pulses with energies as high as 1 microJ, durations of 45 fs, nearly diffraction limited Gaussian spatial profiles, and power stability smaller than 2% RMS of the generated sidebands were obtained. These multicolor sidebands can be used in various experiments, such as multicolor pump-probe experiment.
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Affiliation(s)
- Jun Liu
- Department of Applied Physics and Chemistry and Institute for Laser Science, University of Electro-Communications, Chofu, Tokyo, Japan.
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36
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Zhong F, Jiang H, Gong Q. Tuning the frequency of few-cycle femtosecond laser pulses by molecular phase modulation. OPTICS EXPRESS 2009; 17:1472-1477. [PMID: 19188976 DOI: 10.1364/oe.17.001472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We demonstrate theoretically how the time-dependent phase modulation induced by molecular alignment can be used to tune the frequency of few-cycle femtosecond laser pulses continuously. Using impulsively excited alignment in N(2), the central wavelength of an initial 800 nm, 5 fs Gaussian pulse can be tuned from 324.6 to 4237.3 nm. The aligned N(2) molecules are obtained by pretransmitting another 800 nm, 100 fs linearly polarized laser pulse of intensity 3.5x10(13) Wcm(-2). The number of optical cycles contained in the frequency-tuned pulse is almost unchanged after ideal chirp compensation.
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Affiliation(s)
- Fengjiao Zhong
- Department of Physics, Peking University, Beijing, PR China
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37
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Liu J, Kobayashi T. Cascaded four-wave mixing and multicolored arrays generation in a sapphire plate by using two crossing beams of femtosecond laser. OPTICS EXPRESS 2008; 16:22119-22125. [PMID: 19104648 DOI: 10.1364/oe.16.022119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Ultrabroadband signals were found to be generated by cascaded four-wave mixing in a bulk medium by using two crossing femtosecond laser pulses. As many as fifteen spectral upshifted pulses and two spectral downshifted pulses were obtained with spectral bandwidth broader than 1.5 octaves. Bright upshifted pulses were observed on both sides of the two crossing beams. Two dimensional multicolored arrays were observed for the first time in a sapphire plate medium.
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Affiliation(s)
- Jun Liu
- Department of Applied Physics and Chemistry and Institute for Laser Science, University of Electro-Communications, Chofugaoka 1-5-1, Chofu, Tokyo 182-8585, Japan.
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38
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Chen Y, Marceau C, Théberge F, Châteauneuf M, Dubois J, Chin SL. Polarization separator created by a filament in air. OPTICS LETTERS 2008; 33:2731-2733. [PMID: 19037408 DOI: 10.1364/ol.33.002731] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We demonstrate that a femtosecond laser pulse-induced filament can act as a "polarization separator" for a copropagating femtosecond probe pulse. The probe component with polarization parallel to the pump is guided along the propagation axis through the cross interactions with the pump pulse. And the probe component with polarization orthogonal to that of the pump is diffracted out into an outer ring by the plasma. The extinction ratio (I(probe)(min) / I(probe)(max)) along the propagation axis is better than 1:20.
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Affiliation(s)
- Yanping Chen
- Centre d'Optique, Photonique et Laser (COPL) and Département de Physique, de Génie Physique et d'Optique, Université Laval, Québec, Québec G1V 0A6, Canada.
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39
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Xi TT, Lu X, Zhang J. Spatiotemporal moving focus of long femtosecond-laser filaments in air. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:055401. [PMID: 19113181 DOI: 10.1103/physreve.78.055401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 04/24/2008] [Indexed: 05/27/2023]
Abstract
The characteristics of filaments formed by femtosecond-laser pulses freely propagating in air are different from those of filaments generated with a focal lens. A scheme combining (2D+1) modeling of the nonlinear Schrödinger equation and ray-tracing method is proposed to provide a fast estimate of the long-range filamentation process in a single-filament regime. A filament with a length of more than 100m is formed by a 10-mJ , negative chirped 350-fs laser pulse freely propagating in air. A ray-tracing calculation based on the refractive index field obtained from the nonlinear Schrödinger simulation shows that, in the 100-m propagation range, the main mechanism of filamentation is the spatiotemporal moving focus induced by the initial distribution of the laser intensity. The analysis of ray trajectories suggests that the energy exchange between background and filament core due to refocusing of light rays can be induced by Kerr self-focusing without the help of the ionization effect. The plasma defocusing can be observed only at a very short distance on the propagation track, and it prevents the collapse of the laser field.
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Affiliation(s)
- Ting-Ting Xi
- Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
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40
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Théberge F, Châteauneuf M, Ross V, Mathieu P, Dubois J. Ultrabroadband conical emission generated from the ultraviolet up to the far-infrared during the optical filamentation in air. OPTICS LETTERS 2008; 33:2515-2517. [PMID: 18978905 DOI: 10.1364/ol.33.002515] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Ultraviolet and infrared conical emissions were observed during the filamentation in air of powerful femtosecond laser pulses produced by a portable terawatt laser system. The broadband spectrum was measured from 200 nm up to 14 microm and covered the complete optical transmission window of the atmosphere. The angularly resolved spectrum showed some X-wave structure across the frequency range analyzed. However, we demonstrated that the strong conical emission observed in the mid- and far-infrared is mainly owing to the four-wave mixing between the pump pulse and its blueshifted conical emission.
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41
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Zhang X, Jiang H, Chen L, Jiang Y, Yang H, Gong Q. Wavelength femtosecond light pulse generated from filamentation-assisted fourth-order nonlinear process in potassium titanyl phosphate crystal. OPTICS LETTERS 2008; 33:1374-1376. [PMID: 18552964 DOI: 10.1364/ol.33.001374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A femtosecond light pulse at 480 nm in wavelength was generated during filamentation of an intense 808 nm femtosecond laser pulse propagating along the x axis and polarized between the y and z axes of a KTP crystal. It was proven that the parametric amplification process by a fourth-order nonlinear polarization (chi(4)(omega(2),omega,omega,omega,-omega(1)) induces frequency generation at 480 nm, where the pump light comes from the incident laser and the seed light comes from the generated supercontinuum by filamentation. The wavelength of the generated signal could be turned from 460 to 520 nm by adjusting the propagation direction in the crystal.
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Affiliation(s)
- Xipeng Zhang
- Department of Physics and State Key Laboratory for Mesoscopic Physics, Peking University, Beijing, China
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42
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Valtna H, Tamosauskas G, Dubietis A, Piskarskas A. High-energy broadband four-wave optical parametric amplification in bulk fused silica. OPTICS LETTERS 2008; 33:971-973. [PMID: 18451956 DOI: 10.1364/ol.33.000971] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Efficient broadband four-wave optical parametric amplification in bulk Kerr medium (fused silica) is demonstrated by means of noncollinear phase matching and cylindrical focusing geometry without the onset of beam breakup and filamentation. Amplified signal energy as high as 180 microJ with 1 ps, 1.8 mJ pumping at 1,055 nm is achieved with pump-to-signal energy conversion close to 10%. More than 70 nm FWHM parametric gain bandwidth around 740 nm is demonstrated without imposing angular dispersion on the frequency components of the broadband seed signal.
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Affiliation(s)
- H Valtna
- Department of Quantum Electronics, Vilnius University, Sauletekio Avenue 9, Bldg. 3, LT-10222 Vilnius, Lithuania
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43
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Kosma K, Trushin SA, Schmid WE, Fuss W. Vacuum ultraviolet pulses of 11 fs from fifth-harmonic generation of a Ti:sapphire laser. OPTICS LETTERS 2008; 33:723-725. [PMID: 18382530 DOI: 10.1364/ol.33.000723] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We demonstrate that in a short Ar cell, generation of the fifth harmonic from 12 fs pulses at 810 nm directly results in ultrashort vacuum UV pulses at 162 nm. They have a spectral width of approximately 5 nm and a duration of 11+/-1 fs (1.4 times the transform limit), as measured by cross correlation with the fundamental pulses. Their energy (estimated to 4 nJ) turned out to be sufficient for use as a pump in time-resolved experiments.
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Affiliation(s)
- Kyriaki Kosma
- Max-Planck-Institut für Quantenoptik, D-85748, Garching, Germany.
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44
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Bergé L, Skupin S. Sub-2 fs pulses generated by self-channeling in the deep ultraviolet. OPTICS LETTERS 2008; 33:750-752. [PMID: 18382539 DOI: 10.1364/ol.33.000750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The generation of sub-2 fs light pulses in the UV is numerically demonstrated, using frequency conversion in filamentation regime. Few-cycle pulses emitted at 266 nm keep their temporal shape over several tens of centimeters. Self-compression results from the interplay between Kerr self-focusing and a low-density plasma, which continuously defocuses the pulse over extended propagation ranges.
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Affiliation(s)
- L Bergé
- Department of Theoretical Physics and Application, CEA/DAM Ile de France, Bruyeres-le-Chatel, Arpajon cedex, France.
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45
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Volkov RV, Khakhulin DV, Savel'ev AB. Four-wave parametric conversion of femtosecond laser pulse in a filament induced in a solid target. OPTICS LETTERS 2008; 33:666-668. [PMID: 18382511 DOI: 10.1364/ol.33.000666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Nonlinear interaction of two femtosecond laser pulses in a filament, induced by one of them inside a fused silica plate, leads to generation of the new spectral components. These spectral components reach hundreds of nanometers bandwidth. Their spatial and spectral properties can be explained by four-wave parametric coupling in the filament. The energy measurements indicate the high efficiency of this process.
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Affiliation(s)
- Roman V Volkov
- Department of Physics and International Laser Centre, M.V. Lomonosov Moscow State University, Vorob-evy Gory, Moscow, Russia.
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Bergé L, Skupin S. Few-cycle light bullets created by femtosecond filaments. PHYSICAL REVIEW LETTERS 2008; 100:113902. [PMID: 18517787 DOI: 10.1103/physrevlett.100.113902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Indexed: 05/26/2023]
Abstract
We report a generic mechanism of light bullet formation during the filamentation of femtosecond pulses. This mechanism is tested for gaseous and dense media. It allows the production of robust, sub-10 fs structures of light with no post-compression stage. By coupling an infrared pump with a seed beam, tunable pulses with durations down to a few femtoseconds can be generated by parametric processes.
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Affiliation(s)
- L Bergé
- Département de Physique Théorique et Appliquée, CEA-DAM/Ile de France, BP 12, 91680 Bruyères-le-Châtel, France.
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Faccio D, Averchi A, Lotti A, Di Trapani P, Couairon A, Papazoglou D, Tzortzakis S. Ultrashort laser pulse filamentation from spontaneous X-Wave formation in air. OPTICS EXPRESS 2008; 16:1565-1570. [PMID: 18542233 DOI: 10.1364/oe.16.001565] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The description of ultrashort laser pulse filamentation in condensed media as a spontaneous formation of X waves is shown to apply also to filaments generated in air. Within this framework, a simple explanation is brought for several features of the filament such as the subdiffractive propagation and the energy flux from the weakly localized tails of the X-waves to the intense core.
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Affiliation(s)
- Daniele Faccio
- CNISM and Department of Physics and Mathematics, Università dell'Insubria, Via Valleggio 11, IT-22100 Como, Italy.
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Chen Y, Théberge F, Kosareva O, Panov N, Kandidov VP, Chin SL. Evolution and termination of a femtosecond laser filament in air. OPTICS LETTERS 2007; 32:3477-3479. [PMID: 18087514 DOI: 10.1364/ol.32.003477] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The evolution of the filamentation of a femtosecond laser pulse in air is measured. The divergence of the filament core is almost constant over a long distance, encompassing a zone with efficient ionization followed by another where ionization is much weaker. At the end, the core diverges out linearly with a low divergence due to self-spatial filtering.
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Affiliation(s)
- Yanping Chen
- Centre d'Optique, Photonique et Laser (COPL) and Département de physique, Université Laval, Québec, Québec G1K 7P4, Canada.
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Trisorio A, Hauri CP. Control and characterization of multiple circularly polarized femtosecond filaments in argon. OPTICS LETTERS 2007; 32:1650-2. [PMID: 17572735 DOI: 10.1364/ol.32.001650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We provide what is believed to be the first experimental evidence of spatial control on multiple filamentation (MF) using circularly polarized femtosecond laser pulses. The exceptional shot-to-shot reproducibility of the MF pattern allowed complete characterization of the two copropagating high-energy filaments, revealing for the first time temporal (self-) compression of circularly polarized filamenting pulses to a fifth of the initial 57 fs laser pulse duration without any sophisticated chirp control. Compared with LP MF, an enhancement in spatial stability and an increase in energy throughput are reported for circular input polarization.
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Affiliation(s)
- A Trisorio
- Laboratoire d'Optique Appliquée, ENSTA-Ecole Polytechnique, CNRS UMR 7639, Palaiseau, France
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Faccio D, Averchi A, Dubietis A, Polesana P, Piskarskas A, Di Trapani P, Couairon A. Stimulated Raman X waves in ultrashort optical pulse filamentation. OPTICS LETTERS 2007; 32:184-6. [PMID: 17186058 DOI: 10.1364/ol.32.000184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We demonstrate that ultrashort pulse filamentation in liquids with strong Raman gain leads to the spontaneous formation of nonlinear X waves at a Raman-shifted wavelength. We measured as much as 75% energy conversion efficiency into a Raman X wave in ethanol starting from 1 ps pulses due to the group velocity matching between the pump and Raman X pulses. Large Raman gain of a weak seed signal was observed in water, associated with a strong spatiotemporal transformation of the seed into an X wave.
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Affiliation(s)
- Daniele Faccio
- Consorzio Nazionale Interuniversitaro per le Scienze della Materia, Como, Italy.
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