Phase-matched lossy microring resonator add/drop multiplexers

摘要

Phase matching of the signal paths between input and drop ports significantly improves filter characteristics and results in a box-like passband and a deeply suppressed, flat stopband. As a result add/drop multiplexers built with only two filter elements, each consisting of a chain of one, two, or three series coupled microrings exhibit satisfactory filter characteristics and very moderate degradation due to resonator loss. Accurate phase matching however requires thermooptic or electrooptic tuning, usually embedded in one arm of the multiplexer. Analytical and simulated results are presented covering transmission and group delay characteristics, sensitivity to waveguide loss and free spectral range (FSR) extension techniques. A temperature/stress sensor application is also proposed.