双锥型光纤布喇格光栅光谱特性

Optical-spectrum Characteristics of a Biconical Fiber Bragg Grating

利用传输矩阵法和有限元法分析了光栅周期、调制深度、锥腰直径和不同设计区段长度比等光栅制作参量和结构设计参量对双锥型光纤布喇格光栅光谱特性的影响.软件仿真结果表明:限定相关参量后,光栅周期增大,双锥型光纤布喇格光栅整体反射谱右移,与均匀分布光纤布喇格光栅光谱变化规律一致;调制深度增强,两主反射峰基本不变,而两主反射峰中间的次级峰个数增多,光强增大;锥腰直径减小,激发更多包层模,干涉峰个数增多,强度提升;整根光栅长度保持1cm不变,锥腰区,标准光栅区和渐变光栅区长度比直接影响次级峰的数量和幅值,随着渐变光栅区长度占比的增大,次级峰的幅值增大,同时个数减少.双锥型光纤布喇格光栅可在多参量传感器、多通道滤波器、多通道半导体激光器、色散补偿和光上下载分插复用等方面广泛应用.

Using transfer matrix method and finite element method, the influences of fabrication and structure factors, such as grating period, modulation depth, diameter of waist and length ratio in different regions, on the spectral characteristics of the biconical fiber Bragg grating were analyzed. The simulation results demonstrate that when other grating factors remain unchanged, the reflection spectrum of the biconical fiber Bragg grating red-shifts with the increasing of grating period. This change trend is in accord with that of the uniform fiber Bragg grating. However, when the modulation depth is enhanced, the two main peaks does not shift, but the number of secondary peaks between the two main peaks increases and intensity is enhanced. Moreover, with the decrease of the cone waist diameter, more cladding modes are excited, and more interference peaks with enhanced intensity are observed. When the grating length is kept at 1 cm, the length ratios between waist region, standard grating region and gradient grating region will impact the number and the amplitude of the secondary peaks directly. With the increase of the gradient grating region length, the number of secondary peak decreases but the amplitude increases. In a word, by properly designing the grating factors, the biconical fiber Bragg grating can be widely used in multi-parameter sensors, multi-channel filters, multi-channel semiconductor laser, dispersion compensation and OADM.