Waveguide self-coupling based reconfigurable resonance structure for optical filtering and delay

Abstract

We propose a novel waveguide self-coupling based reconfigurable resonance structure that works as a flat-top second-order tunable filter and a tunable delay line with low group delay dispersion. The high-order resonance features result from the mutual mode coupling between the clockwise and counter-clockwise resonance eigenmodes. The transfer-matrix method is used to theoretically analyze the device optical performances. The relations between the two embedded phase shifters for achieving flat-top filtering and group delay responses are given. As the coupled resonances are provided by only one physical resonator, the device is inherently more compact and resilient to fabrication errors compared to conventional microring resonators. Phase tuning for its reconfiguration is also simpler and more power-efficient.