Mid-infrared spectroscopy of laser filamentation in optics

This work seeks to explore the interplay between material differences in the nonlinear index of refraction n2 and zero group velocity dispersion wavelength λGVD in the formation of spectral broadening and supercontinuum generation. We present mid-wave infrared (MWIR) spectroscopic data of the transmitted 200 fs (FWHM) laser pulse through polycrystalline zinc selenide and polycrystalline zinc sulfide (Cleartran™) optical materials. Using MWIR laser wavelengths between 3.3 and 3.8 μm, we vary the laser energy between roughly 1 and 126 μJ and focus the laser pulses into the materials using lenses of four different focal lengths. This allows us to analyze not only how the nonlinear frequency broadening of the fundamental wavelength varies with increasing pulse energy, but also how it varies with increasing peak intensities when the pulse energy is kept fixed. These results are discussed along with possible implications on the importance of both laser energy and peak intensity in producing supercontinuum for a material with a given n2 and λGVD. Understanding of these practical considerations is essential for assessing material effects to MWIR ultrashort pulsed lasers.

[1]  A. Couairon,et al.  Multi-octave spanning nonlinear interactions induced by femtosecond filamentation in polycrystalline ZnSe , 2017 .

[2]  Govind P. Agrawal,et al.  Nonlinear mechanisms of filamentation in broad-area semiconductor lasers , 1996 .

[3]  See Leang Chin,et al.  Ultrafast white-light continuum generation and self-focusing in transparent condensed media , 1999 .

[4]  J. Moloney,et al.  Effective three-wave-mixing picture and first Born approximation for femtosecond supercontinua from microstructured fibers , 2010 .

[5]  Gaeta.  Catastrophic collapse of ultrashort pulses , 2000, Physical review letters.

[6]  A. Becker,et al.  Intensity clamping of a femtosecond laser pulse in condensed matter , 2002 .

[7]  J. Marburger,et al.  Self-focusing: theory , 1975, International Quantum Electronics Conference, 2005..

[8]  Ranka,et al.  Observation of Pulse Splitting in Nonlinear Dispersive Media. , 1996, Physical review letters.

[9]  M. Kolesik,et al.  Critical power for self-focusing in the case of ultrashort laser pulses , 2013 .

[10]  G Fibich,et al.  Critical power for self-focusing in bulk media and in hollow waveguides. , 2000, Optics letters.

[11]  Robert W. Boyd,et al.  Self-focusing : past and present : fundamentals and prospects , 2009 .

[12]  R R Alfano,et al.  Generation of infrared supercontinuum covering 3-14 microm in dielectrics and semiconductors. , 1985, Optics letters.

[13]  F. Smektala,et al.  Filament-induced visible-to-mid-IR supercontinuum in a ZnSe crystal: Towards multi-octave supercontinuum absorption spectroscopy , 2016 .

[14]  S. Diddams,et al.  Broadband Mid-IR Standoff Spectroscopy of Explosives with a Femtosecond Optical Parametric Oscillator , 2012 .

[15]  E. Rosencher,et al.  Random quasi-phase-matching in bulk polycrystalline isotropic nonlinear materials , 2004, Nature.

[16]  Vytautas Jukna,et al.  Ultrafast supercontinuum generation in bulk condensed media , 2017 .

[17]  A. A. Kaminskii,et al.  Second optical harmonic generation in nonlinear crystals with a disordered domain structure , 2001 .

[18]  Audrius Dubietis,et al.  Even and odd harmonics-enhanced supercontinuum generation in zinc-blende semiconductors , 2018, Journal of the Optical Society of America B.

[19]  Self-channeling of ultrashort laser pulses in materials with anomalous dispersion. , 2005, Physical review. E, Statistical, nonlinear, and soft matter physics.

[20]  Junichiro Kono,et al.  Extreme midinfrared nonlinear optics in semiconductors. , 2001 .

[21]  Govind P. Agrawal,et al.  Nonlinear Fiber Optics , 1989 .

[22]  I. Walmsley,et al.  The role of dispersion in ultrafast optics , 2001 .

[23]  J V Moloney,et al.  Physical factors limiting the spectral extent and band gap dependence of supercontinuum generation. , 2003, Physical review letters.

[24]  E. W. Stryland,et al.  Sensitive Measurement of Optical Nonlinearities Using a Single Beam Special 30th Anniversary Feature , 1990 .

[25]  L. Bergé,et al.  Self-guiding of femtosecond light pulses in condensed media: Plasma generation versus chromatic dispersion , 2006 .

[26]  Enam Chowdhury,et al.  Ultrafast mid-infrared high harmonic and supercontinuum generation with n2 characterization in zinc selenide. , 2019, Optics express.

[27]  刘建胜,et al.  Few-cycle spatiotemporal soliton wave excited by filamentation of a femtosecond laser pulse in materials with anomalous dispersion , 2006 .

[28]  Michael G. Hastings,et al.  Ultrafast Nonlinear Refraction Measurements of Transparent Materials in the Mid-Infrared for Modeling Harmonic and Supercontinuum Generation , 2019, Nonlinear Optics (NLO).

[29]  J V Moloney,et al.  Unidirectional optical pulse propagation equation. , 2002, Physical review letters.

[30]  E. Wright,et al.  Theory and simulation of supercontinuum generation in transparent bulk media , 2003 .

[31]  A. Dubietis,et al.  Filamentation and light bullet formation dynamics in solid-state dielectric media with weak, moderate and strong anomalous group velocity dispersion , 2016 .

[32]  Jean-Claude Diels,et al.  Ultrashort Laser Pulse Phenomena , 1996 .

[33]  Vladislav V. Yakovlev,et al.  Zinc selenide: an extraordinarily nonlinear material , 2018, OPTO.

[34]  J. Rothenberg.  Pulse splitting during self-focusing in normally dispersive media. , 1992, Optics letters.

[35]  A. Yi,et al.  Time-resolved measurement of single pulse femtosecond laser-induced periodic surface structure formation induced by a pre-fabricated surface groove. , 2015, Optics express.

[36]  S. Skipetrov,et al.  Nonlinear optics: Disorder is the new order , 2004, Nature.