多相移间插取样光纤光栅滤波器的设计与优化  

Optimization of Multiple⁃Phase⁃Shifted and Interleaved Sampled Fiber Gratings Filter

作　　者：胡胜 白芯蕊 李莎莎 袁功进 戴润泽 宋海娜 刘聪[1] HU Sheng;BAI Xinrui;LI Shasha;YUAN Gongjin;DAI Runze;SONG Haina;LIU Cong(Hubei University of Technology,Wuhan 430068,China)

机构地区：[1]湖北工业大学,武汉430068

出　　处：《光通信研究》2024年第3期64-70,共7页Study on Optical Communications

基　　金：国家自然科学基金资助项目(62202148)。

摘　　要：【目的】取样光纤布拉格光栅(SFBG)以其梳状滤波特性引起人们的普遍关注,成为光纤光栅技术研究的新热点。显然,设计具有高通道数、平顶和窄带宽的光学滤波器具有重要的工程意义。文章提出了一种插入多相移(MPS)的间插取样光纤布拉格光栅(ISFBG)滤波器。【方法】ISFBG具有大量反射通道,通过插入MPS,可引入多个平顶窄传输通道。通过优化插入ISFBG的两个π相移的位置,首先设计了具有41个传输通道的光学滤波器,该滤波器覆盖C波段,通道间隔为100 GHz,每个传输通道都具有平顶响应,3 dB带宽较窄(<1 GHz),形状因子较小(<3.2)。接着,保持其他结构不变,通过优化插入3个π相移的位置,可在此基础上进一步减小形状因子,从而改善传输通道的矩形形状。通过引入MPS技术,设计了插入3个π相移的ISFBG,可实现通道数目加倍,通道间隔减半。【结果】演示了一种通道数目为81的平顶窄带宽的光学滤波器,该滤波器覆盖C波段,通道间隔为50 GHz,多通道的3 dB带宽为900.5 MHz,形状因子接近2.17。同时讨论了MPS的大小、位置和光纤的等效长度的精度对于实际制造的影响。【结论】所设计的滤波器具有较高通道数,每个通道都具有平顶响应且带宽较窄,符合设计目的。这种滤波器在多波长激光器和多波段微波信号处理系统中具有潜在的应用前景。【Objective】Due to its comb filter characteristics,Sampled optical Fiber Bragg Grating(SFBG)has attracted wide spread attention and become a new focus in the research of optical fiber grating technology.The research work on designing optical filters with high channel numbers,flat tops,and narrow pass bands is of great importance in practical situation.Consequently,an Multi⁃Phase Shift Interpolated Sampling optical Fiber Grating(MPS⁃ISFBG)filter is proposed.【Methods】ISFBG has a large number of reflection channels and can introduce multiple flat top narrow transmission channels by inserting multi⁃phase shift.By optimizing the location of the twoπphase⁃shift distributions of the inserted ISFBGs,an optical filters with 41 transmission chan nels was designed which covers the C⁃band with a channel interval of 100 GHz.Each channel has a flat⁃top response,a narrow 3 dB bandwidth(<1 GHz)and a small shape factor(<3.2).With structure parameters unchanged,threeπphase shifts are insert ed,which can further reduce the shape factor,thus improving the rectangular shape of the transmission channel.Finally,doubling the number of channels with half of the channel interval is achieved by introducing the MPS technique and inserting threeπphase shifts into the ISFBG.【Results】The filter with 81 channels flat⁃top narrow bandwidth covering the C⁃bands with 50 GHz channel spacing is demonstrated.The 3⁃dB bandwidths of the multiple channels are 900.5 MHz and the shape factors are close to 2.17.Meanwhile,the effect of the magnitude of the multiphase shift,the location and the equivalent length of the fiber on the actual fab rication is discussed.【Conclusion】The designed filter has a large number of channels.Each channel has a flat⁃top response and narrow bandwidth,in line with the design purpose.Such filters have potential applications in multi⁃wavelength lasers and multi wave microwave signal processing systems.

关 键 词：光滤波器 多通道 平顶窄带宽 相位调制 多相移间插取样光纤布拉格光栅 

分 类 号：TN256[电子电信—物理电子学]