Optimum Design of Asymmetric Birefringent Interleaver Based on FIR Digital Filter Design Technique

FIR is adopted to design the asymmetrical birefringent interleaver. By choosing appropriate value of structure parameters such as crystal deflection angle, thickness and angle of analyser, we have managed to design an asymmetrical interleaver, the ratio of output port (wide bandwidth) to another output port (narrow bandwidth) at 3 dB passband (bandwidth ratio) is 2.06. The simulation results are given and the influence of each crystal´s azimuth angle, thickness, and analyser´s azimuth angle on the whole interleaver are analysed. The analysis on designing method and simulation results show that in the asymetrical birefringent interleaver, the thickness of crystal affects bandwidth of passband and channel isolation of output spectrum more than crystal´s and analyser´s azimuth angles.