三级双泵结构光纤ASE光源输出光谱平坦度的改善

Improving the output spectral flatness of fiber ASE source with three-stage double-pump configuration

为满足光纤布拉格光栅(FBG)传感和波分复用(WDM)光纤通信系统对光源光谱平坦度与带宽的要求,利用调整优化结构参数和增益均衡滤波方法,对三级双泵浦结构掺铒光纤(EDF)放大自发辐射(ASE)光源输出光谱进了行平坦化处理。通过对三段EDF长度优化和两级正反向泵浦功率的调整,使得光源输出光谱覆盖C+L波段,消除了1 570nm附近的光谱凸起;并根据输出光谱特性设计了一种基于长周期光纤光栅(LPFG)的增益平坦滤波器(GFF),对输出光谱进行二次平坦处理,进一步消除了EDF峰值吸收波长1 532nm处的光谱凸起。在C+L波段内获得了0.76dBm的光谱平坦度,光谱3dB带宽达80nm以上。

In order to satisfy the demands for the spectral bandwidth and flatness of light source in fiber Bragg grating （FBG） sensing and wavelength division multiplexing （WDM） fiber optic communication system,using the method of adjusting structural parameters and gain filtering technique, the output spec- trum of erbium-doped fiber amplified spontaneous emission （ASE） source with three-stage double-pump configuration is flattened. Through optimizing the lengths of three stages of erbium-doped fibers （EDFs） and adjusting the forward and backward pump power, the output spectrum covers conventional-wave length band （C-band） and long-wavelength band （L-band）,and the spectral protrusion near 1 570 nm is flattened. Meanwhile,according to the characteristics of the output spectrum, we design a long period fi- ber grating （LPFG）-based gain flattening filter,and eliminate the spectral protrusion near the 1 532 nm absorption peak of EDF, which is the secondary flattening for the output spectrum. The results show that the ASE spectral flatness is better than 0.76 dBm,and the 3 dB spectral bandwidth is more than 80 nm in C＋ L-band.