全光纤干涉式传感结构作为一种新兴的高灵敏度和高光学集成性光纤传感器, 由于其传感特性与其结构密切相关, 使传感器设计更加灵活, 因此, 传感机理及如何提高测量性能成为研究该类传感器的关键。文章利用有限差分光束法得到全光纤干涉式传感结构中传感光纤部分去包层和弯曲时的输出光谱, 再通过傅里叶变换得到空间频谱情况与色散方程进行比对, 最终获得两种增敏方式下主要参与耦合包层模的情况。结果表明, 相较于未增敏前, 增敏后参与耦合的包层模数量有所增多, 阶数有所增高, 且在一定范围内, 弯曲半径越大, 主要参与耦合的包层模阶数越高。

Due to the advantages of small volume and simple structure,the cladding mode of the in-fiber interference sensor is used widely. Therefore, the investigation of the sensing mechanism and improvement of the measurement performance are the key factors to study this sensor. By using the finite difference beam propagation method, the interference spectrum of the sensors with removing partial of cladding and bending are simulated in this paper. The order of dominant cladding mode is obtained by comparing dispersion equation and spatial frequency spectrum after Fourier transform. The results show that, compared with normal sensor, the orders and numbers of cladding modes both increase. Meanwhile, with the increasing of bending radius within limits, the cladding modes order increase.