The experimental and theoretical investigation of the generation of an ultra broadband optical pulse in a microstructure fiber

本项目的目的是：1）利用感应相位调制在微结构光纤中产生超宽带光脉冲; 2）通过理论和实验的比较，了解微结构光纤中光谱调制的机理。主要研究结果如下：1）利用互相关频率分辨光学门控装置测量了钛宝石激光器输出的超宽带光脉冲在锥形光纤中的相位和幅度。实验结果与频域有限差分法计算结果进行了比较。计算结果表明，输入光纤的光脉冲在锥形光纤中发生分裂，产生了基孤子脉冲。2）利用感应相位调制，将钛宝石激光振荡器输出的基脉冲与其二次谐波脉冲在微结构光纤中共同传输，观察到二次谐波脉冲的光谱展宽。特别地，当这些脉冲在芯径为1.0 μ m的光子晶体光纤中共同传输时，观察到了从380 nm到1000 nm的超宽带脉冲的产生。测量了二次谐波脉冲的延迟时间对光谱展宽的依赖关系，并与计算结果进行了比较。从计算中，人们发现，产生的基本孤子脉冲的基本脉冲的分裂和基本孤子脉冲的光谱峰值位置的产生的定时强烈修改的二次谐波脉冲的延迟时间。

The aims of this project were 1)the generation of an ultra broadband optical pulse in a microstructure optical fiber by the use of induced-phase modulation and 2)the comparison between theory and experiment to understand the mechanism of the spectral modulations in a microstructure fiber. The research results are summarized as follows.1)The phase and amplitude of an ultra broadband optical pulse generated by propagating an optical pulse from a Ti : Sapphire laser oscillator in a taper fiber were measured by a cross-correlation frequency-resolved optical gating apparatus. The experimental results were compared with calculations obtained by a finite-difference in the frequency domain method. These results agreed well and the calculations showed that a fundamental soliton pulse was generated in a taper fiber by the fission of the optical pulse inputted in a fiber.2)The spectral broadening of a second-harmonic pulse was observed when a fundamental pulse and its second-harmonic pulse from a Ti : Sapphire laser oscillator were co-propagated in a microstructure fiber by the use of induced-phase modulation. Especially, the generation of an ultra broadband pulse from 380 nm to 1000 nm was observed when these pulses were co-propagated in a 1.0-μm-core-diameter photonic crystal fiber. The dependence of the spectral broadenings on the delay times of the second-harmonic pulse was measured and compared with calculations. From the calculations, it was found that the timings of the generation of a fundamental soliton pulse created by the fission of a fundamental pulse and the spectral peak position of the fundamental soliton pulse were strongly modified by the delay times of the second-harmonic pulse.