High Performance Optical Filters Using Three Waveguide Coupled Sagnac Loop Reflectors

TL;DR

This paper presents a theoretical study of multi-functional integrated photonic filters based on three waveguide coupled Sagnac loop reflectors, demonstrating their ability to achieve diverse high-performance spectral filtering functions.

Contribution

It introduces a novel design of 3WC-SLR resonators for advanced spectral filtering, with detailed analysis of their performance and fabrication tolerances.

Findings

Achieves ultrahigh spectral extinction ratios and slope rates.

Enables resonance mode splitting with high ERs and low free spectral ranges.

Supports classical filter types like Butterworth, Bessel, Chebyshev, and elliptic.

Abstract

We theoretically investigate advanced multi-functional integrated photonic filters formed by three waveguide coupled Sagnac loop reflectors (3WC-SLRs). By tailoring the coherent mode interference, the spectral response of the 3WC-SLR resonators is engineered to achieve diverse filtering functions with high performance. These include optical analogues of Fano resonances that yield ultrahigh spectral extinction ratios (ERs) and slope rates, resonance mode splitting with high ERs and low free spectral ranges, and classical Butterworth, Bessel, Chebyshev, and elliptic filters. A detailed analysis of the impact of the structural parameters and fabrication tolerances is provided to facilitate device design and optimization. The requirements for practical applications are also considered. These results theoretically verify the effectiveness of using 3WC-SLR resonators as multi-functional integrated photonic filters for flexible spectral engineering in diverse applications.