双带通啁啾光纤光栅光谱特性仿真及分析

Spectral simulation of double-bandpass chirped fiber Bragg grating

针对啁啾光纤光栅的带通滤波特性,设计了纤芯/包层复合结构的啁啾光纤光栅滤波器。基于光纤耦合模和传输矩阵理论及坐标变换方法,对其光谱特性进行仿真分析,验证了该光栅的双带通滤波特性;对周期为536、537、538nm,长度为8、10、12mm,折射率调试深度为0.0002、0.0003、0.0004,啁啾系数为0.05、0.10、0.15nm/cm的该结构光栅进行光谱模拟,证明中心波长随周期增大而增大;半峰宽度随长度、调制深度、啁啾系数增大而变宽;反射率峰值随啁啾系数增大而降低,随调制深度增大而升高。上述研究证明了该结构光栅具有双带通滤波特性,且幅值带宽可调。

According to the band-pass filtering characteristics of chirped fiber Bragg gratings,a fiber core/cladding composite chirped fiber Bragg gratings filter is designed.Firstly,the spectral characteristics are simulated and analyzed based on the fiber coupling mode,transmission matrix theory and coordinate transformation method,and the double band-pass filtering characteristics of the grating are verified.Then,the spectra of the fiber core/cladding composite structures with periods of 536,537 and 538 nm,grating lengths of 8,10 and 12 mm,refractive index modulation depth of 0.0002,0.0003 and 0.0004,chirp coefficients of 0.05,0.10 and 0.15 nm/cm were simulated.The half-peak width increases with the grating length,refractive index modulation depth and chirp coefficient.The peak reflectance increases with the increase of refractive index modulation depth and decreases with the increase of chirp coefficient.It is proved that this grating has double band-pass filtering characteristics and its amplitude bandwidth is adjustable.