Design and Simulation of Thermo-Optic Phase Shifters with Low Thermal Crosstalk for Dense Photonic Integration

We investigate and demonstrate the thermal crosstalk problem in integrated photonic circuits with metal and silicon doped heaters. Further, we illustrate that due to the localized heating effect, integrated doped heaters are out-performed in terms of thermal crosstalk as compared to integrated metal heaters. To mitigate thermal crosstalk and enhance phase tuning efficiency further, a CMOS compatible air-filled trench region is realized between the doped heater and the adjacent element. The performances of three fundamental building blocks of integrated photonic circuits, namely, a PN phase shifter, an optical attenuator, and a ring resonator, are tested by full-wave thermal, charge, and optical simulations. Additionally, the impact of thermal crosstalk on the performance of integrated PN phase shifters and optical attenuators is examined thoroughly. The proposed low crosstalk thermal phase shifters might be very beneficial for densely routed complex integrated photonic circuits like photonic transceivers for data centers, optical phased array antennas, and photonic reservoirs.