Experimental study on the chirped structure of the white-light continuum generation by femtosecond laser spectroscopy
Quan Dong-Hui (全冬晖)a, Liu Shi-Lin (刘世林)a, Zhang Lei (张蕾)b, Yang Jian (杨健)b, Wang Li (汪力)b, Yang Guo-Zhen (杨国桢)b, Weng Yu-Xiang (翁羽翔)b
a Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China; b Institute of Physics, Chinese Academy of Sciences, Beijing 100080,China
Abstract The chirped structure of the white-light continuum generation (WLCG) pulse produced by focusing 800nm laser pulse with a pulse duration of 150fs (FWHM: full-width-at-half-maximum) onto a 2.4 mm thick sapphire plate was investigated by the optical Kerr gate technique with normal hexane as the optical Kerr gate medium. The observed WLCG was positively chirped, the measured anti-Stokes spectrum of WLCG ranges from 449 to 580nm with a temporal span of 2.56ps. When using metal reflecting mirrors to eliminate the group velocity dispersion (GVD) effect, we found that a span of 1.3ps still remained, indicating that the chirped pulse cannot be accounted for simply by GVD of the pulse propagation in the dispersive media. Our results suggest that the light-induced refractive index change due to the third-order nonlinear optical effect leads to an additional positive group velocity dispersion, which contributes to an important portion of the observed temporal broadening of the chirped WLCG. In addition to using reflective optical elements instead of dispersive optical elements, an effective way of reducing the chirp is to minimize the optical path length of the WLCG medium.
Received: 26 May 2003
Accepted manuscript online:
PACS:
42.65.Re
(Ultrafast processes; optical pulse generation and pulse compression)
(Beam characteristics: profile, intensity, and power; spatial pattern formation)
Cite this article:
Quan Dong-Hui (全冬晖), Liu Shi-Lin (刘世林), Zhang Lei (张蕾), Yang Jian (杨健), Wang Li (汪力), Yang Guo-Zhen (杨国桢), Weng Yu-Xiang (翁羽翔) Experimental study on the chirped structure of the white-light continuum generation by femtosecond laser spectroscopy 2003 Chinese Physics 12 986
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