增益平坦滤波器在掺铒光纤光源中的应用

Application of gain flattening filters in Erbium-doped fiber source

掺铒光纤光源的输出光谱有两个不对称峰,但光源的应用一般都要求有比较平坦的增益输出。借鉴EDFA的增益平坦技术,简述了几种增益平坦滤波器的工作原理及优缺点,包括电介质薄膜滤光片、光纤光栅滤波器、马赫-曾德尔滤波器、光子晶体光纤光栅滤波器和基于高双折射光纤环形镜的滤波器。指出目前采用长周期光纤光栅和电介质薄膜滤光片作为光纤光源的滤波器是比较适合的选择。最后以电介质薄膜滤光片为例,给出了C波段掺铒光纤光源增益平坦的实验结果,并与滤波前做了对比分析。实验表明,滤波器的加入使光纤光源获得了增益平坦的输出光谱。

The output spectrum of Erbium-doped fber source has two unsymmetrical peaks. The application of fiber source usually requires flat gain. Based on the gain flattening technologies of erbium doped fiber amplifier（EDFA）, the working principle and its characteristics of several gain flattening filters were discussed. They were dielectric thin film filters, fiber gratings filters, Mach-Zehnder interferometer filters, photonic crystal fiber grating filters and high birefringence fiber loop mirror filters. The paper pointed out that the long-period fiber gratings and the dielectric thin film filters are currently proper filters for fiber source. In the end, the gain flattening experiments of C-band fiber source based on dielectric thin film filter were showed. The output performances of fiber source before and after filtering were given and analyzed. The results show that gain flattened spectrum of fiber source is obtained using filter.