Numerical investigation of slow solitons in Bragg gratings with a hyperbolic tangent apodization

This paper numerically and analytically investigates the formation and propagation motion of optical soliton in the Bragg grating. We choose the fibre Bragg grating with hyperbolic tangent apodization in the middle section in order to obtain slower solitons. Optical fibre soliton but not Bragg grating soliton is used as input pulse in the discussion, which is much more approximate to the light source for the practical purpose. We discuss in detail the effects of the soliton＇s velocity with some parameters in the process of transmission. The results show that by choosing special parameters, one can make the soliton slow-down with a little distortion and energy decay and obtain tunable time-delay on a small scale.

光纤光栅中孤子时延特性研究

从光纤光栅慢光产生的物理机理和非线性耦合模方程组,仿真分析了均匀布拉格光栅中光栅孤子传输时的减速特性;利用高速示波器搭建了测量高能量、窄脉冲通过布拉格光纤光栅后时延特性的实验系统,分别测量了由普通单模光纤和高非线性光纤制作的均匀光栅对光脉冲的时延特性。实验结果为:用5 cm长普通单模光纤制作的布拉格光栅可以使在其中传输的光脉冲产生426 ps的时延,而相同长度高非线性布拉格光纤光栅对光脉冲的时延量为1.639 ns。计算后可知,光脉冲在对应光栅中的传输速度分别约为1.17×108m/s和0.31×108m/s。结果说明光纤光栅能够实现光速减慢,而且高非线性光纤光栅对光脉冲的减速效果要好于普通单模光纤制作的光栅。