微纳米高折射率涂敷层对长周期光纤光栅传输谱特性的影响

基于模式耦合理论，通过求解给定参数的覆盖高折射率微纳米涂敷层长周期光纤光栅( LPFG)的频谱，分析了四层模型LPFG中微纳米高折射率涂敷层对其传输谱特性的影响。研究结果表明：通过设计涂覆层厚度、涂覆层折射率变化范围以及LPFG包层厚度等参数，包层模将进入高折射率微纳米涂敷层中进行传输，在LPFG传输谱出现模式迁移现象；随着涂覆层折射率的增大，谐振峰波长向短波长方向漂移；LPFG包层半径越小，谐振峰波长对涂覆层折射率变化的响应灵明度越高。

Tuning Effects of Micro/nano High Refractive Index Overlay on the Transmission Spectra of Long Period Fiber Gratings

Tuning effects of micro/nano high refractive index overlay on the transmission spectra of long period fiber gratings( LPFG) with given parameters are theoretically analyzed and numerically simulated by using coupled model theory. The results show that the phenomena of mode transition appear when the cladding mode entering the high refractive index overlay for transmission through properly designing the overlay thickness, overlay refractive index change range,and LPFG coating thickness. With the increase of the refractive index of the overlay,resonance peaks shift towards the shorter wavelength. The smaller the overlay radius,the higher the sensitivity of the resonance peaks in response to refractive index of the overlay.