Dual-ring resonator design for enhanced thermal isolation and optical performance

Abstract

We report on the design of a dual-ring resonator for enhanced thermal isolation between rings and associated improved optical performance. Two 20 µm diameter silicon (Si) ring resonators, each embedded in silicon dioxide (SiO2) and having a semi-circular arc-shaped overclad heater, are spaced apart by 200 nm as a base configuration. The optimization of the topology of a surrounding 4 µm deep custom air trench results in a 10.3°C increase in the steady-state average temperature of a specified heated ring relative to the thermal performance of the baseline structure. An additional thermal isolation trench between rings in combination with a thermally conductive overlay structure is also investigated and shown to provide further enhanced anisotropic heat flow control and device transient response. From an optical perspective, the custom trench plus thermal overlay strategy for heat transfer enhancement reduces the throughput at the device drop port by −3.36 dB across the double-ring structure and produces a 37% larger difference between ring resonances when comparing performance with a simply heated, non-etched device design.