弯曲曲率对长周期光纤光栅透射谱特性的影响

报道了一种分析长周期光纤光栅(LPFG)透射谱谐振波长和衰减率随弯曲曲率变化的方法。利用耦合模理论和微扰近似推导了长周期光纤光栅透射谱随弯曲曲率变化的一般表达式,得到当弯曲曲率为2.56 m~(-1)时,长周期光纤光栅透射谱分裂,分裂峰的谐振波长和衰减率与弯曲曲率呈非线性变化,但分裂峰的间距与弯曲曲率呈线性变化。利用B-Ge共掺单模光纤写入的长周期光纤光栅证实了理论的正确性,且具有很好的重复性。

Effect of Bending Curvature on Transmission Spectra of Long Period Fiber Gratings

A method to analyze the resonant wavelength and damping decrement of the transmission spectrum of long period fiber grating (LPFG) with bending curvature was reported.Based on coupled mode theory and perturbation approximation,the general expression of transmission spectrum of LPFG according to bend curvature is deduced. Furthermore,the transmission spectrum of the hended LPFG is found to be splitting when the bending curvature is 2.56 m~(-1).The resonant wavelength and decrement of the split peaks change nonlinearly with the bending curvature,but the distance between split peaks changes linearly withthe bending curvature.The LPFG written on the B-Ge co-doping single mode fiber proves the theory.