Switchable and Flexible Comb Filter/Interleaver Based on Ring-Resonators With Tunable Couplers

We demonstrate a switchable and flexible comb filter/interleaver based on ring-resonator (RR) in which the directional couplers are replaced by tunable couplers. The tunable coupler is composed of an even-arm-length Mach-Zehnder interferometer (MZI) with a micro-heater embedded in one of the arms. For the sake of discussion, we convert the heating power of the micro-heater into a pure phase shift value independent of the waveguide material and size. By changing the phase shift value, the filter can be switched between comb filter and interleaver. Meanwhile, the insertion loss (IL), full width at half maximum (FWHM), extinction ratio (ER), and the shape of the response spectrum can also be reconfigured. The switchable and flexible comb filter/interleaver may provide a potential application in dense wavelength division multiplexing (DWDM) optical communication systems.