Design and analysis of a narrowband filter for optical platform

This paper presents an approach to designing narrowband digital fil-ters that are realizable using optical allpass building blocks. We de-scribe a top-down design method by explicitly examining the deriva-tion of an Infinite Impulse Response (IIR) architecture. Our result demonstrates a design that can achieve a 0.0025π passband edge while providing 60dB stopband attenuation. The design is aimed to reduce filter pole magnitudes, providing tolerance for waveguide losses and fabrication errors. The narrowband filter is based on the foundation of latticed allpass sections, which makes it naturally re-alizable using basic photonic components. Furthermore, analysis is performed on delay length variations that can result from the fabri-cation process. Index Terms — Allpass filters, eigenfilters, optical waveguide filters, delay effects, interpolatio