光通信系统要求可调谐光滤波器(TOF)隔离度高, 偏振敏感性低, 目前基于角度调谐滤光片技术的TOF 很难满足这一要求。通过膜系仿真分析了此类TOF 透射谱劣化的原因。针对不同偏振态的光束在倾斜入射时中心波长及带宽分离现象, 提出一种对称反转光路对TOF 透射谱进行优化, 可在整个透射范围内(C 波段)将TOF 的隔离度提高到30 dB 以上, 偏振相关损耗减少至0.2 dB 以下。同时由于光路的对称性, 不同偏振光光程相同, 避免了添加额外的波片补偿装置。研制样品经过测试, 实现了C 波段内96 个ITU-T 通道的调谐, 实验所得结果与理论相吻合。

Optical communication system requires the high isolation and low polarization sensitivity of Tunable Optical Filter (TOF). At present, the most of TOF based on thin film are hard to meet this requirement. The reason of TOF transmission spectrum degradation is analyzed by simulation. Referring to the center wavelength and bandwidth separation when different polarization beam in tilted incidence, an optimization design is proposed based on symmetric optical path. It improves the isolation of TOF to more than 30 dB, and restrains the polarization dependent loss within 0.2 dB. Meanwhile, different polarization beam have the same optical path because of the symmetric optical path, which can avoid adding additional wave plate. The module performance is tested, which realizes that 96 ITU-T channels can be tuned in the range of C band. The experiment results are in good agreement with the analytical ones.