柚子型光子晶体光纤啁啾光栅的反射谱特性

利用有限元法和传输矩阵法,对柚子型结构的光子晶体光纤啁啾光栅的反射谱进行了理论分析。得到了啁啾光栅参数和光纤参数对光子晶体光纤啁啾光栅反射谱的影响规律。结果表明随着啁啾系数和折变量的增加,光栅反射谱呈规律变化,当啁啾系数增大到一定程度时几个反射峰会连到一起,形成一个大的反射带宽。光纤的内包层直径和纤芯直径的改变能够影响各反射峰之间的间距。同时研究了切趾变迹对光子晶体光纤啁啾光栅反射谱的影响,研究表明,所用切趾函数会同时对多个峰进行切趾,每个峰的切趾效果都很好。对反射谱波动较大的几个峰相连的啁啾光栅经过柯西切趾后反射谱曲线平滑,适合于实际应用。

Reflection Spectrum Characteristics of the Grapefruit-Type Photonic Crystal Fiber Chirped Grating

Based on the finite element method and transmission-matrix method, the reflection spectrum of the grapefruit-type photonic crystal fiber chirped grating is analyzed theoretically. The influences of the fiber grating parameters and fiber structural parameters on the reflection spectrum characteristics of the photonic crystal fiber chirped grating are analyzed. The results show that with the increase of the chirp coefficient and refractive indexes modulation, the reflection spectrum changes regularly. When the chirp coefficient increases to a certain extent, the several reflection peaks can be connected together to form a large reflection band. The spacing between the reflection peaks can be changed by the inner-cladding diameter and the core diameter of the photonic crystal fiber. At the same time, the influence of apodization on reflection spectrum of the photonic crystal fiber chirped grating is discussed. Studies show that the apodization function can apodize several peaks and the apodization effect of each peak is very good. For fiber grating with several peaks connected, the wave of its reflection spectrum is large. But through the Cauchy apodization, the reflection spectrum curve is smooth, which is suitable for practical applications.