Three Coupled Waveguide Sagnac Loop Reflectors for High Performance
Integrated Optical Filters
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.
