Thermal modeling of electrically-pumped continuous-wave microring resonator-based topological insulator lasers

Deleterious effects caused by Joule heating in electrically-pumped continuous-wave InP-based topological insulator lasers based on two-dimensional microring resonator arrays are estimated in this theoretical study. Steady-state temperature distributions within such an array are developed using a full numerical solution. Thermal interactions between active gain regions and ring resonators pose significant operational and integration challenges, as these devices are extremely sensitive to temperature-induced changes in a material's index of refraction. Designing such an array benefits from clear understanding on the effects of systematic non-uniform heating profiles due to temperature variations among the rings. This paper first presents the thermal modeling of a single isolated ring under electrical pumping and then discusses its impact on an operational array composed of 10 × 10 such rings. The simulation results reported here were benchmarked against experimental measurements of the mircoring lasers, wherever possible. Calculations based on a tight-binding model for the array suggest that the laser exhibits single-mode optical output with the preservation of topological properties up to 4 times the threshold current. The useful operating range of the array is mainly limited by the thermal shifts of wavelengths in addition to the wavelength disorders due to fabrication imperfections.