超短脉冲光通过光折变体光栅衍射及透射光强的瞬时变化特性研究

Instantaneous Characteristics of Diffraction and Transmission of Photorefractive Grating Illuminated by Ultra-short Pulse Laser

采用Kogelnik的耦合波理论,研究了超短脉冲光通过光折变体光栅的衍射及透射光强在时域的瞬时变化特性.发现衍射和透射脉冲波形与读出脉冲宽度、光栅周期、光栅厚度及光折变材料的折射率调制大小有密切关系.通过调整这些参量的数值,可以获得需要的脉冲形状.同时还发现衍射和透射脉冲在时间轴上有一定的偏移,偏移量的大小与参量选择有关.

Based on the coupled wave theory of Kogelnik, the time-domain diffraction and transmission of PR gratings were theoretically studied when they were illuminated by ultra-short pulse laser. The waveforms of the diffracted and transmitted pulses depend on the parameters of readout pulse duration, grating spacing,crystal thickness and modulation of the refractive index were found. By changing values of these parameters,the diffracted and transmitted waveforms could be controlled to satisfy our desires. It is found that the diffracted and transmitted pulses have a displacement along the t-axis, and the value depends on those parameters.