一种沿表面膜系厚度线性变化型介质膜滤波器

A Thin Film Filter with Variable Coating Thickness Along Surface

研究一种沿表面膜系厚度线性变化型介质薄膜滤波器（TFF）.从理论分析了介质层相对于基底的倾斜角对滤波片偏振相关损耗（PDL）、调谐偏移、带宽、通带纹波及插入损耗的影响.设计制作了高精度的调谐控制驱动电路,在1 531.6～1 667.9 nm的调谐范围内的3 dB带宽为0.6 nm,20 dB带宽小于3 nm,调谐误差小于0.1 nm,插入损耗小于2.8 dB（光纤到光纤）,取得了接近恒定的传输特性.

A thin film filter（TFF） in which each layer thickness varies along surface,is presented in this paper. The effect of variable coating thickness on the filter characteristics, such as polarization dependent losses（PDL）, tuning offset, bandwidth, pass band ripple and insertion loss,is analyzed. Hardware circuit has been designed to control wavelength tuning for the filter. With many advantages such as stable 3 dB bandwidth （0.6 nm） ,narrow 20 dB bandwidth （〈3 nm） ,low tuning offset （〈0. 1 nm）, low fiber to fiber insertion loss （〈2.8 dB）, nearly constant transmission characteristics are demonstrated over 1 531.6-1 667.9 nm experimentally.