Three Waveguide Coupled Sagnac Loop Reflectors for Advanced Spectral Engineering

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, spectral response of 3WC-SLR resonators is engineered to achieve diverse filtering functions with high performance. These include optical analogues Fano resonances that yield ultrahigh extinction ratios (ERs) and slope rates, resonance splitting ERs low free ranges, classical Butterworth, Bessel, Chebyshev, elliptic filters. A detailed analysis impact structural parameters fabrication tolerances provided facilitate device design optimization. The requirements for practical applications are also considered. results verify effectiveness using as flexible engineering in applications.