Wavelength-tunable operation of magneto-optical switch consisting of amorphous silicon microring resonator on garnet

A microring resonator (MRR) can enhance optical modulation and reduce a device's footprint in photonic integrated circuits. However, optical devices composed of MRRs have narrow operation bandwidths. Furthermore, the resonant wavelength of the MRR is highly sensitive to variations in ambient temperature. In this study, we experimentally demonstrate a magneto-optical (MO) microring switch with wavelength tunability. The switch consists of a hydrogenated amorphous silicon (a-Si:H) MRR on an MO single crystalline garnet, Ce:YIG. By controlling an external magnetic field generated from an integrated electromagnetic coil, nonreciprocal phase shifts in the Ce:YIG are induced and an MO switch is successfully operated with low power consumption owing to the structure, compared with the conventional design. Moreover, by combining both MO and thermo-optic effects, the broadband wavelength-tunable operation of switching is achieved without an additional heater. (C) 2019 The Japan Society of Applied Physics