Design of optical finite impulse response filter generating arbitrary spectrum output

TLDR: In this article, a procedure for the synthesis of an optical finite impulse response (FIR) birefringent filter generating arbitrary spectral output is presented, which is equally applicable for any periodic transfer function whose corresponding impulse response is real and causal.

Abstract: In the present communication, a procedure for the synthesis of an optical finite impulse response (FIR) birefringent filter generating arbitrary spectral output is presented. The basic filter consists of a cascaded system of n identical retarders between two polarizers at the two ends. A mathematical model of the optical FIR filter is introduced using the FIR theory of digital filter design. The parameters determined by the synthesis procedure are the angles of the optic axes of the individual crystals and the angle of the output polarizer. Classical FIR filter design method along with the optical backward transfer technique has been used. Two different arbitrarily specified spectral output profiles have been studied. However, the method is equally applicable for any periodic transfer function whose corresponding impulse response is real and causal.