Theory and experiment of flat-top all-fiber comb filter based on two high birefringence fiber Sagnac loop filters

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• 作者：Guorong Qiao^a ; Zhigang Cao^a ; Rui Wang^a ; Xiaochun Ji^a ; Bing Gao^a ; Jun Peng^b ; Feng Xu^a ; Benli Yu^a ; ^{benliyu@ahu.edu.cn}
• 关键词：Flat-top comb filter ; Switchable channel spacing ; High birefringence fiber Sagnac loop filter
• 刊名：Optics Communications
• 出版年：2012
• 期刊代码：50_00304018
• 类别：ph
• 出版时间：1 June, 2012
• 卷：285
• 期：12
• 页码：2836-2839
• 文件大小：826 K

摘要

A simple flat-top all-fiber comb filter based on two high birefringence fiber (HBF) Sagnac loop filters is presented. The proposed flat-top comb filter consists of two HBF Sagnac loop filters with two polarization controllers (PCs) and a fiber circulator. According to the theoretical analysis, with proper settings of the polarization state of the PCs, the comb filter can realize flat-top passband and the channel spacing also can be switched when the comb filter is convex spectrum. The 0.3 dB bandwidth of the flat-top passband is 0.49 nm with a free spectral range of 1.4 nm. The maximum extinction ratio is nearly 20 dB. The comb filter with switchable channel spacing can be obtained from 0.7 nm to 1.4 nm.