800 nm飞秒激光长周期光纤光栅的特性

利用800 nm飞秒激光脉冲作为光源，在标准通信单模光纤上直接刻写周期分别为100，200，300和400 m的长周期光纤光栅(LPFG)，得到波长范围为1 280～1 680 nm的透射谱，分析研究了在不同刻写条件下LPFG透射谱的共振波长、透射深度和插入损耗等参数的变化。通过对比分析发现透射衰减与刻写长度、条数以及平台高度等有着一定的对应关系。优化实验参数制作出共振波长分别约为1 407，1 311，1 669，1 551 nm，透射深度分别约为24.0,22.3，27.8，23.4 dB，插入损耗分别约为2.5，1.7，3.2，2.0 dB的LPFG。

Spectra of long-period fiber grating fabricated by 800 nm femtosecond laser pulses

Long-period fiber gratings(LPFGs) with the periods of 100, 200, 300 and 400 μm were fabricated in standard telecommunication fibers in air using laser direct writing method. Spectra of the LPFGs from 1 280 nm to 1 680 nm were obtained under different experimental conditions, in which the resonant wavelengths, the maximum transmission losses and the insertion losses were observed. By optimizing the experimental parameters, LPFGs were fabricated with the resonant wavelengths of 1 407, 1 311, 1 669, and 1 551 nm, respectively. The maximum transmission losses were about 24.0 ， 22.3 ， 27.8 , and 23.4 dB, and the insertion losses were about 2.5 ， 1.7 ， 3.2 ， and 2.0 dB, respectively.