多相移和级联光纤光栅透射光谱特性研究

Transmission spectral characteristic studying of multi-phase migration and cascaded fiber Bragg

基于耦合模理论,利用传输矩阵法,系统地分析了多相移和级联相移光纤光栅的透射谱特点。结果表明,相移光纤光栅可在透射谱阻带中打开一个或多个透射窗口,多个相移时,透射窗口数等于相移的个数。改变相移量的大小可以改变输出光波长,而且随着相移量的增加,多相移和级联情况下,透射窗口向长波方向移动。光栅的级联使得其在布喇格衍射波长处,打开一个极窄的透射窗口,透射率与级联个数有关,当级联数为4时,透射率最高。

The transmission spectrum of multiple and cascaded phase-shifted fiber bragg grating are analyzed systematically based on the coupled-mode theory with the transfer matrix method. It shows that in the transmission spectrum of the shifted fiber bragg grating, there are one or multiple transmission windows with narrow line width. The number of the transmission windows is equal to the number of the phase shifts of the grating. And with the increasing of the magnitude of the phase shift of the grating, the wavelength of the transmission window shifts to the longer wavelength. For cascaded phase-shifted fiber bragg grating, with the increas- ing of the magnitude of the phase shift, the transmissivity of the center wavelength is concerned with the number of the cascaded phase-shifted. And as the number of the cascaded phase-shifted is 4, the maximum transmissivity was obtained.