光学滤波器用超窄带光纤光栅的光谱性能研究  

Study on Spectral Properties of Ultra-Narrow-Band Fiber Bragg Gratings for Optical Filters

作　　者：李璇[1] 应康[1] 苏庆帅 张柳欣 皮浩洋[1] 王迪[2] 蔡海文[1,3] 叶青 Li Xuan;Ying Kang;Su Qingshuai;Zhang Liuxin;Pi Haoyang;Wang Di;Cai Haiwen;Ye Qing(Key Laboratory of Space Laser Communication and Detection Technology,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;National Key Laboratory of Science and Technology on Space Microwave,CAST,Xi’an,Xi’an 710100,Shaanxi,China;Zhangjiang Laboratory,Shanghai 201210,China)

机构地区：[1]中国科学院上海光学精密机械研究所空间激光传输与探测技术重点实验室,上海201800 [2]中国空间技术研究院西安分院空间微波技术国家级重点实验室,西安710100 [3]张江实验室,上海201210

出　　处：《中国激光》2023年第14期170-177,共8页Chinese Journal of Lasers

基　　金：国家重点研发计划(2020YFB0408300);国家自然科学基金(62175246,61805260);上海市自然科学基金(22ZR1471100);中国科学院青年创新促进会基金(YIPA2021244)。

摘　　要：超窄带光纤布拉格光栅作为一种重要的无源光纤器件,可以作为优良的光学滤波器。首先在理论分析的基础上,模拟在光纤布拉格光栅制备过程中引入不同的不均匀紫外辐照,分析不同紫外光辐照分布函数下的光栅光谱性能,并采用逐点扫描紫外辐照法在不同的辐照不均匀条件下刻写光纤布拉格光栅。结果表明:紫外辐照的不均匀会极大地影响光纤光栅的光谱性能(带宽、矩形度及边模抑制比等参数),紫外辐照越不均匀,光纤光栅的3 dB带宽和25 dB带宽都越大,光谱矩形度变差,边模抑制比降低,光学滤波器的性能也更差。提出通过对切趾函数进行修正来补偿辐照不均匀的影响。采用该方法能补偿紫外光斑以及光路调整等带来的刻写误差,使得光纤光栅的谱型得到优化,将光纤光栅的边模抑制比提高到30 dB以上,满足光学滤波器的应用需求。Objective Ultra-narrow-band optical filters are key components for signal processing in the fields of microwave photonics,coherent communication and dense wavelength-division multiplexing.The ideal ultra-narrow-band optical filter has a rectangular frequency response composed of an ultra-flat passband and a very steep edge.The flat passband has high signal fidelity and can prevent the signal from being distorted,whereas the steep edge can suppress the crosstalk between adjacent bands.Fiber Bragg gratings(FBGs)that achieve various frequency responses are commonly used in bandpass optical filters owing to their small size,low insertion loss and compatibility with other optical fiber devices and systems.However,for the application of ultra-narrow-band optical filters,the spectral and performance parameters of FBG are extremely demanded to obtain the rectangular spectral response with flat passband and high side-mode suppression ratio(SMSR).In the process of FBG fabrication,the stability of the writing optical path,the uniformity of the ultraviolet(UV) spot and the accuracy of apodization process are highly required whether the UV irradiation method of the phase mask or the point-by-point scanning method is adopted.The writing error will lead to the reduction of the spectral performance of the grating,which directly affects the quality of the signal.Therefore,the influence of UV irradiation inhomogeneity on the spectral properties of FBG is analyzed in this paper.Methods Solid-state laser point-by-point writing method is used for the fabrication of uniform narrow-band optical FBG.The uniformity of UV spot and the accuracy and stability of the optical path will affect the optical fiber grating refractive index modulation distribution,thus affecting the performance of FBG spectrum.By theoretical simulation,the influence of different UV irradiation inhomogeneity on the spectrum of FBG is analyzed.The apodization function is modified based on the analysis results to compensate for the effect of irradiation inhomogeneity,

关 键 词：光栅 光纤器件 光纤布拉格光栅 光纤光栅制备 光学滤波器 

分 类 号：TN253[电子电信—物理电子学]