光纤布拉格光栅自致啁啾效应的研究

根据耦合模理论,采用传输矩阵法分析了相位掩模法制作的光纤布拉格光栅的反射谱特性.设计了一种新的写制光纤光栅的光路,利用高斯激光光束写制出具有短波自致啁啾效应的切趾光栅(栅长0.015 m).对具有短波自致啁啾效应的光纤光栅进行了物理切割(剩余光栅的长度分别取0.007 m和0.0055 m),得到了一种新型的具有长波自致啁啾效应的光纤光栅.原本的自致啁啾光栅反射谱中旁瓣分布在短波长方向,而得到的新型自致啁啾光栅的反射谱中长波长方向的旁瓣更为明显.基于对光纤布拉格光栅自致啁啾效应的分析,提出一种新型类高斯切趾函数,以此函数对自致啁啾效应进行数值模拟,得到了与实验结果相一致的光谱图.

Study on Self-Induced Chirping for Fiber Bragg Grating

Based on coupled mode theory, the reflection properties of the fibre Bragg grating fabricated with phase mask are analysed by transfer matrix method. A new beam path is designed to fabricate fiber gratings and a new short-wavelength self-induced chirping apordized grating with length of 0.015 m is fabricated by Gaussian ultraviolet (UV) beam. Furthermore, a new long-wavelength self-induced chirping grating is obtained by cutting the original fiber grating shorter to 0.007 m and 0.0055 m separately. By contrast with the original grating, the new one has more side lobes on the long-wavelength side of the reflection spectrum and the side-lobes on the short-wavelength side are suppressed. On the basis of analysis of the new self-induced chirping grating, a new type of Gaussian-like apodization function is presented and used to simulate the self-induced chirping of the fiber grating. The theoretical results accord with the experimental results.