机械诱导长周期光纤光栅的透射特性分析

Analysis of transmission characteristics of mechanically induced long-period fiber grating

研究辅助光纤、纵向拉力和涂覆层对机械诱导长周期光纤光栅(MILPFG)透射特性的影响.实验结果表明,MILPFG的透射谱峰值与压力呈sin2(κl)关系,中心波长发生蓝移,带宽呈抛物线变化,但无辅助光纤时,产生相同透射谱峰值时所需的压力更小;纵向拉力增大时,MILPFG的透射谱峰值几乎不变,但其中心波长线性减小,带宽呈指数增大;相同压力下,有涂覆层时MILPFGs的透射谱峰值和中心波长较小,边带损耗也较小.因此,无需辅助光纤,在纵向施加一定拉力,即可在涂覆的光纤上制作出优良的MILPFG.

The impacts of assistant fiber,its longitudinal pretension and fiber coating on the transmission characteristics of mechanically induced long-period fiber gratings（MILPFGs）were investigated.It was shown by experimental result that the transmission spectra peaks of MILPFGs have a relationship of sin2（κl）with the pressure,the central wavelengths have a blueshift,and the bandwidths change parabolically.But the necessary pressure is smaller for generate the same transmission spectra peak when there is no assistant fiber.The transmission spectra peak is almost unchanged when the longitudinal pretension is increased.But the central wavelength decreases linearly and the bandwidth increases exponentially.The peak of transmission spectra and central wavelength of MILPFGs are smaller when they are induced in coated fibers than that in uncoated ones under the same pressure,and the out-of-band loss is also smaller.So the MILPFGs should be induced in coated fibers when an assistant fiber is absent,meanwhile,a small pretension should be applied.