理论研究飞秒激光脉宽、啁啾和初始光谱对其在熔融石英中成丝产生的超连续光谱的影响。结果表明:在固定能量下,脉宽越大,蓝移截止波长越长,光谱强度越低。对脉宽大于150 fs的激光,负啁啾脉冲比无啁啾和正啁啾脉冲产生的蓝移光谱强度更大。
The influences of the pulse duration, chirp, and initial spectrum of the femtosecond laser on the supercontinuum generated in fused silica have been investigated theoretically. Results show that, with the increase of the pulse duration, the cut-off wavelength of the blue-extension becomes longer and the spectral intensity becomes lower at the constant energy. For the laser with pulse duration larger than 150 fs, the spectral intensity of the blue-extension generated by the negatively chirped pulse is higher than those generated by the freely-chirped pulse and the positively chirped pulse.
[1] Couairon A, Mysyrowicz A. Femtosecond filamentation in transparent media[J]. Physics Reports, 2007, 441(2-4):47-189.
[2] Kasparian J. White-light filaments for atmospheric analysis[J]. Science, 2003, 301(5629):61-64.
[3] Tu H H, Boppart S A. Coherent fiber supercontinuum for biophotonics[J]. Laser & Photonics Reviews, 2013, 7(5):628-645.
[4] Demmler S, Rothhardt J, Heidt A M, et al. Generation of high quality 1.3 cycle pulses by active phase control of an octave spanning supercontinuum[J]. Optics Express, 2011, 19(21):20151-20158.
[5] Li D W, Zhang L Z, Xi T T, et al. High spectral energy density supercontinuum generation in fused silica by interfering two femtosecond laser beams[J]. Journal of Optics, 2019, 21(6):065501.
[6] Borrego-Varillas R, Romero C, Mendoza-Yero O, et al. Femtosecond filamentation in sapphire with diffractive lenses[J]. Journal of the Optical Society of America B, 2013, 30(8):2059-2065.
[7] Chang J W, Xu M N, Wang D, et al. Control of filament by shaped femtosecond pulses in fused silica[J]. Acta Optica Sinica, 2019, 39(1):0126021.
[8] Zhan L D, Xu M N, Xi T T, et al. Contributions of leading and tailing pulse edges to filamentation and supercontinuum generation of femtosecond pulses in air[J]. Physics of Plasmas, 2018, 25(10):103102.
[9] Bergé L, Mauger S, Skupin S. Multifilamentation of powerful optical pulses in silica[J]. Physical Review A, 2010, 81(1):013817.
[10] Skupin S, Bergé L. Supercontinuum generation of ultrashort laser pulses in air at different central wavelengths[J]. Optics Communications, 2007, 280(1):173-182.
[11] Nuter R, Skupin S, Bergé L. Chirp-induced dynamics of femtosecond filaments in air[J]. Optics Letters, 2005, 30(8):917.
[12] Sun Q, Asahi H, Nishijima Y, et al. Pulse duration dependent nonlinear propagation of a focused femtosecond laser pulse in fused silica[J]. Optics Express, 2010, 18(24):24495-24503.
[13] Calendron A L, Çankaya H, Cirmi G, et al. White-light generation with sub-ps pulses[J]. Optics Express, 2015, 23(11):13866-13879.
[14] Rolle J, Bergé L, Duchateau G, et al. Filamentation of ultrashort laser pulses in silica glass and KDP crystals:a comparative study[J]. Physical Review A, 2014, 90(2):023834.
[15] Malitson I H. Interspecimen comparison of the refractive index of fused silica[J]. Journal of the Optical Society of America, 1965, 55:1205-1208.