Single-shot measurement of free-electron laser polarization at SDUV-FEL

In this paper, a division-of-amplitude photopolarimeter(DOAP) for measuring the polarization state of a free-electron laser(FEL) pulse is described. The incident FEL beam is divided into four separate beams, and four Stokes parameters can be measured in a single-shot. In the crossed-planar undulators experiment at the Shanghai deep ultraviolet FEL test facility, this DOAP instrument constructed in house responsed accurately and timely while the polarization-state of fully coherent FEL pulses were switched, which is helpful for confirming the crossed-planar undulators technique for short-wavelength FELs.     

Propagation dynamics of nonlinear chirped optical laser pulses in a two-level medium

We investigate the propagation dynamics of nonlinear chirped optical laser pulses in a two-level medium. For certain chirp strength and chirp width, an incident 2π nonlinear chirped pulse will split into optical precursors and a stable self-induced transparency soliton. This is caused by the particular Fourier spectrum that includes not only central resonant frequency components but also high-frequency and low-frequency sidebands. Moreover, the effects of chirp parameters on the evolution of nonlinear chirped pulses are also discussed.     

级联光纤布拉格光栅光谱特性研究

从耦合模理论出发,用传输矩阵的方法数值模拟分析了二级联、三级联的光纤布拉格光栅的反射谱和透射谱特性,实验测得的结果与理论模拟的结果基本吻合.