基于包层旋转折变型光纤光栅的动态增益均衡器

提出并利用高频CO₂激光脉冲在普通单模通信光纤上写出了包层旋转折变型长周期光纤光栅(R-LPFG). 在分析R-LPFG波导结构和双折射特性的基础上，对光栅周期数和折变旋转度分别为50和7.2°/周期的R-LPFG进行了实验研究.结果表明，这种类型的光栅可极大地降低其谐振波长对横向负荷不同作用方向所表现出的方向相关性，并且其谐振峰幅度横向负荷灵敏度在任意方向下均高达0.37dB/(g·mm^-1) ，是普通LPFG横向负荷灵敏度的9倍左右.利用R-LPFG的温度线性响应特性和独特的横向负荷特性，设计并实验研究了一种动态增益均衡器，用其平坦掺铒光纤放大器增益谱，在C波段32nm范围内，其平坦度小于±0.5dB，可满足实际环境对通信系统的平坦应用要求.关键词：光纤通信技术长周期光纤光栅动态增益均衡旋转折变

All fiber dynamic gain equalizer based on a fiber grating with rotary refractive index change

An all-fiber dynamic gain equalizer for flattening Er-doped fiber amplifiers based on a long period fiber grating (LPFG) with rotary refractive index change induced by high-frequency CO₂ laser pulses is reported, for the first time to our knowledge. Experimental results show that its transverse load sensitivity is up to 0.37dB/(g·mm^-1), which is 9 times higher than that of a normal LPFG induced by the same method. In addition, it is found that the strong orientation-dependence of the transverse load sensitivity of the normal LPFG reported previously has been weakened considerably. Therefore, such a dynamic gain equalizer based on the transverse load and temperature characteristics of this novel LPFG provides a much larger adjustable range and makes packaging of the gain equalizer much easier. A demonstration has been carried out to flatten an Er-doped fibre amplifier to ±0.5dB over a 32nm bandwidth.