Advanced Three Waveguide Sagnac Loop Reflectors for High Performance Optical Filters
We theoretically investigate advanced multi-functionalintegrated photonic filters formed by three waveguide coupledSagnac loop reflectors (3WC-SLRs). By tailoring the coherentmode interference, the spectral response of the 3WC-SLRresonators is engineered to achieve diverse filtering functionswith high performance. These include optical analogues of Fanoresonances that yield ultrahigh spectral extinction ratios (ERs)and slope rates, resonance mode splitting with high ERs and lowfree spectral ranges, and classical Butterworth, Bessel,Chebyshev, and elliptic filters. A detailed analysis of the impactof the structural parameters and fabrication tolerances isprovided to facilitate device design and optimization. Therequirements for practical applications are also considered.These results theoretically verify the effectiveness of using 3WCSLRresonators as multi-functional integrated photonic filters forflexible spectral engineering in diverse applications.