一种双模光子晶体光纤模间干涉拍长的研究

Research on modular interference beat length for a two-mode photonic crystal fiber

保偏光纤的模间干涉拍长是模间干涉式光纤传感器设计中的关键参数,对于决定光纤的调制长度、传感系统的线性度和动态范围以及模间干涉灵敏度都具有重要作用。本文从理论上对保偏光子晶体光纤(PM-PCF)的模传输特性和模间干涉拍长进行了分析,得到PM-PCF中几个线性偏振模的传输特性和LP11偶模的两个正交偏振模截止波长,并得到了两个低阶线性偏振模LP01模和LP11偶模的模间干涉拍长同波长的关系。并且,对模间干涉拍长进行了实验研究。理论和实验结果表明,模间干涉拍长为×102μm数量级。研究结果可以用于设计稳定的模间干涉光纤传感器。

The modular interference beat length in polarization maintaining photonic crystal fiber（PM-PCF） is a very important parameter for designing fiber sensors based on modular interference.It plays an important role in deciding length modulation,linearity,dynamic range and modular interference sensitivity of fiber sensors.This paper calculates the mode propagation characteristics and modular interference beat length theoretically.The propagation characteristics of several low order modes and two orthogonally polarized cut-off wavelengths of LPe11 in PM-PCF are demonstrated.The relationship between wavelength and modular interference beat length of the PM-PCF is obtained.The experiment is designed to investigate the modular interference beat length in a PM-PCF,and the experiment results show that the beat length is about several hundred microns.