一种模拟双折射可调谐密集波分复用滤波器的设计

提出了一种基于模拟双折射模块的可调谐偏振光干涉型密集波分复用滤波器(DWDM)的新结构。其由置于起偏和检偏器之间的若干个具有相同结构的模拟双折射模块级联构成。每个模拟双折射模块由两个分别用于分束和合束的双折射晶体、放置于其中的两个具有不同折射率的介质块和一个半波片构成。研究了该滤波器的中心频率的可调谐特性。研究表明，利用该结构的滤波器，在满足一定平坦化要求的情况下，如果小角度旋转模拟双折射模块单元，可以在获得大平坦宽度的通带和阻带以及高隔离度的同时简便地实现中心频率的微调谐。实验中，用单级模拟双折射模块验证了该结构的可行性。

Design of a Tunable Dense-Wavelength-Division-Multiplexing Filter Based on Analog Birefringent Structure

A new structure of tunable polarization interference dense wavelength division multiplexing (DWDM) filter based on the analog birefringent module is presented. It is composed of several cascaded analog birefringent modules with the same structure located between two polarizing devices. Each analog birefringent module consists of a pair of birefringent plates for splitting and combination, respectively, and in between a set of two medium plates of different indices of refraction and one half wave plate. The center frequency tunability characteristic of the filter is investigated as well. Results show that as a definite flattening requirement is satisfied, the passband and stopband with wide flatness width and high isolation can be obtained and the center frequency tunability can be accomplished simultaneously when slightly rotating the analog birefringent module unit. The feasibility of the analog birefringent structure is verified through an experiment.