取样光纤布拉格光栅特性的研究

用传输矩阵法从理论上计算了取样光纤布拉格光栅的反射谱特性。这种方法将光栅视为多层均匀薄膜的叠加,利用每一层的传输矩阵相乘获得了光栅的反射谱特性。研究表明,随着光栅长度的增加和采样率、折射率调制深度的减少,反射峰的均匀性得到了改善,旁瓣的反射率变小,带宽明显变窄,而反射峰间隔保持不变。反射峰的间隔由光栅周期决定,与采样率无关,而某些文献则要求采样率小于10%。这与频谱分析所得结论相吻合。

Study on properties of sampled fiber Bragg grating

Reflective spectral properties of sampled fiber Bragg grating is theoretically calculated by transfer matrix method. With this method, the grating is regarded as the overlapping of multi-layer uniform thin film and the reflective spectral properties of the grating are calculated by multiplying transfer matrix of each layer. The study shows that with the increase of grating length and the decrease of sampling rate and refractive index modulation depth, the uniformity of reflective peak will be improved, the reflectance of the side lobes will decrease slightly and the band width will be obviously narrowed but the interval between two reflective peaks is maintained constant. The interval between reflective peaks is determined by grating period and is independent of sampling rate. Some references require that the sampling rate must be less than 10%. This is consistent with the conclusion obtained from spectrum analysis.