任意波长间隔的光纤光栅梳状滤波器设计与实现

采样啁啾光纤光栅理论是实现超高信道数梳状滤波器的理想方案,但是一个啁啾模板只能实现特定波长间隔的光梳状滤波器。提出一种利用光纤布拉格光栅(FBG)直流相移实现任意波长间隔梳状滤波器方法。该方法只需一个啁啾模板与亚微米精度的位移台,在灵活性、简单性和制作成本方面有明显优势。仿真和实验表明FBG直流折射率调制可以引入任意的相位偏移。利用该方法实现了波长间隔为100,50,40GHz的梳状滤波器。最后分析了直流相移光栅长度与相位误差对滤波器边带抑制度的影响。

Design and Implementation of Comb Filter with Arbitrary Channel Spacing Based on Fiber Bragg Gratings

For a given chirp phase mask, only comb filter with special channel spacing can be fabricated. A novel approach to implement arbitrary channel-spacing comb filters based on direct current (DC) phase shift in fiber Bragg grating (FBG) is proposed. Arbitrary channel-spacing comb filter can be achieved by a single chirped phase mask and a submicrometer-precision translation stage. The proposed method is cost-effective, flexible and simple compared to traditional ways. Simulation and experiment show that arbitrary phase shifts introduced by DC refractive index modulation can be achieved. Multichannel comb filter with channel spacing of 100, 50, 40 GHz are implemented with a same phase mask. The impact of DC phase shift length and phase errors on side band suppression ratio are also analyzed.