格结构在晶体梳状滤波器设计中的应用

利用数字信号处理中的格滤波器理论,研究了晶体梳状滤波器的设计方法.当传输函数满足对称和功率互补时,分析指出滤波器的阶数是奇数,N阶滤波器只需要(N+1)/2个波片,且所用波片的厚度比为1∶2∶2…2或2∶2…2∶1；提出了对半带滤波器传输函数作谱分解得到光梳状滤波器传输函数的方法.在此基础上总结出根据应用要求设计晶体梳状滤波器传输函数和结构参量的方法,通过设计一个7阶滤波器,表明提出的方法设计过程简单,且设计结果符合梳状滤波特征.

Synthesis of Crystal Comb Filter Based on Lattice Structure

Based on lattice theory in digital signal processing,a method is presented for synthesizing a crystal-based comb optical filter that is composed of waveplates and polarizers.When the transfer function of filter is symmetrical and power complementary,several significant conclusions about structure of filter are deduced:the filter order must be odd and the length ratio of birefringent waveplates is 1∶2∶2…2 or 2∶2…2∶1,and therefore the number of waveplates that be used only half of filter order.A design algorithm for achieving desired transfer functions is derived by factorizing that of the half-band filter,and then the procedure for synthesis crystal comb filter is proposed.A synthesis example for crystal comb filter is described by which the efficient of the procedure is approved.