基于耦合模理论,利用逆向递推传输矩阵方法,数值研究了光纤光栅透射输出端面存在反射时λ/4相移光栅的开关特性,以及啁啾的引入对其开关性能的影响。研究结果表明：对于反射相干叠加加强,可使λ/4相移光栅的阈值开关能量得到降低,但开关对比度将下降;在λ/4相移光纤光栅中引入负啁啾,能使开关对比度得到较大的提高,但双稳阈值开启能量会增加;引入正啁啾,可进一步降低开关阈值,但开关对比度会下降;啁啾的引入将对λ/4相移光栅的双稳环宽度产生较大影响。

Based on the coupled mode theory, by using the reversely recursive transmission matrix method, the switching characteristics of the λ/4 phase-shifted fiber grating and the influence of introducing chirp on the switching characteristics have been numerically studied when the reflection on the transmission facet is taken into account. For coherent superposition reflection strengthening, it can reduce the threshold switching energy of the λ/4 phase-shifted grating, but the switching contrast will decline. With the introduction of negative chirp in λ/4 phase-shifted grating, the switching contrast is greatly improved, but the bistable threshold switching energy will increase. With the introduction of positive chirp in λ/4 phase-shifted grating, the switching threshold can be further reduced, but the switching contrast will decline. The bistable loop width will be influenced greatly by the chirp.