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

Spectral broadening induced by intense ultra-short pulse in 4H-SiC crystals

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)   

  1. 1 Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    2 State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;
    3 Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
  • 收稿日期:2016-03-01 修回日期:2016-03-23 出版日期:2016-06-05 发布日期:2016-06-05
  • 通讯作者: Xiao-long Chen E-mail:chenx29@iphy.ac.cn
  • 基金资助:

    Project supported by the National High Technology Research and Development Program of China (Grant No. 2014AA041402) and the National Natural Science Foundation of China (Grant Nos. 51272276 and 51322211).

Spectral broadening induced by intense ultra-short pulse in 4H-SiC crystals

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   

  1. 1 Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    2 State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China;
    3 Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
  • Received:2016-03-01 Revised:2016-03-23 Online:2016-06-05 Published:2016-06-05
  • Contact: Xiao-long Chen E-mail:chenx29@iphy.ac.cn
  • Supported by:

    Project supported by the National High Technology Research and Development Program of China (Grant No. 2014AA041402) and the National Natural Science Foundation of China (Grant Nos. 51272276 and 51322211).

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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.

关键词: spectral broadening, SiC, self-phase modulation, intensity-dependent refractive index

Abstract:

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.

Key words: spectral broadening, SiC, self-phase modulation, intensity-dependent refractive index

中图分类号:  (Beam trapping, self-focusing and defocusing; self-phase modulation)

  • 42.65.Jx
42.70.Mp (Nonlinear optical crystals) 42.50.Hz (Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift)