On-Chip Erbium-Doped Tantalum Oxide Microring Hybrid Cavity Single-Mode Laser

TL;DR

This paper reports a high-performance, single-mode Er:Ta2O5 microring laser integrated on silicon, demonstrating high efficiency, narrow linewidth, and stable tuning, advancing on-chip light source technology.

Contribution

It introduces a novel hybrid cavity design with Vernier effect for robust mode selection in Er:Ta2O5 lasers on silicon.

Findings

Achieved a slope efficiency of 2.76%, the highest for Er:Ta2O5 lasers.

Demonstrated stable single-mode tuning from 18°C to 68°C.

Reported a low lasing threshold of 3.3 mW.

Abstract

We demonstrate a high-performance, single-mode Er:Ta2O5 microring laser monolithically integrated on a silicon platform via a customized Damascene process. The Er:Ta2O5 gain medium exhibits a low propagation loss of 0.73 dB/cm and a high intrinsic Q-factor of 5.03 x 105. By utilizing a hybrid cavity_consisting of a microring coupled to a U-shaped waveguide at two symmetric points_we exploit the Vernier effect to achieve robust longitudinal mode selection. Under a non-resonant 1480 nm pumping scheme, the laser yields a side_mode suppression ratio (SMSR) of 53.3 dB and a narrow linewidth of 9.5 pm. A slope efficiency of 2.76 % is achieved_the highest reported to date for Er:Ta2O5 lasers_with a lasing threshold of 3.3 mW. Furthermore, stable single-mode tuning is demonstrated across a temperature range of 18_68 celsius, consistently aligning with theoretical transfer matrix models. This work provides a scalable pathway for high-efficiency, tunable on-chip light sources, bridging the gap for monolithic active-passive integration on the tantalum oxide photonic platform.