Tunable dual-channel filter based on an add-drop resonator Sagnac interferometer

In this paper, we propose an add-drop resonator Sagnac interferometer filter to achieve tunable dual-channel function. Not only is just one ring utilized to control two channels but also the reconfiguration is viable by phase difference control. Three methods are put forward to tune the bandwidth, the extinction ratio, and the reconfiguration of the channels. The reconfiguration of the dual channel is realized via controlling the phase difference between the two arms of the Sagnac interferometer, avoiding the traditional method of shifting the resonance wavelength. Furthermore, the channels can be extended by adding add-drop interferometers. The flexible and compact filter can provide potential implications in dense wavelength division multiplexing systems and optical switches.