中国物理B ›› 2016, Vol. 25 ›› Issue (6): 64206-064206.doi: 10.1088/1674-1056/25/6/064206
• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇 下一篇
Chun-hua Xu(徐春华), Teng-fei Yan(闫腾飞), Gang Wang(王刚), Wen-jun Wang(王文军), Jing-kui Liang(梁敬魁), Xiao-long Chen(陈小龙)
Chun-hua Xu(徐春华)1, Teng-fei Yan(闫腾飞)2, Gang Wang(王刚)1, Wen-jun Wang(王文军)1, Jing-kui Liang(梁敬魁)1, Xiao-long Chen(陈小龙)1,3
摘要:
We report the observation of spectral broadening induced by 200 femtosecond laser pulses with the repetition rate of 1 kHz at the wavelength of 532 nm in semi-insulating 4H-SiC single crystals. It is demonstrated that the full width at half maximum of output spectrum increases linearly with the light propagation length and the peak power density, reaching a maximum 870 cm-1 on a crystal of 19 mm long under an incident laser with a peak power density of 60.1 GW/cm2. Such spectral broadening can be well explained by the self-phase modulation model which correlates time-dependent phase change of pulses to intensity-dependent refractive index. The nonlinear refractive index n2 is estimated to be 1.88×10-15 cm2/W. The intensity-dependent refractive index is probably due to both the nonlinear optical polarizability of the bound electrons and the increase of free electrons induced by the two-photon absorption process. Super continuum spectra could arise as crystals are long enough to induce the self-focusing effect. The results show that SiC crystals may find applications in spectral broadening of high power lasers.
中图分类号: (Beam trapping, self-focusing and defocusing; self-phase modulation)