Silicon-coupled tantalum pentoxide microresonators with broadband low thermo-optic coefficient

Stable microresonators are important integrated photonics components but are difficult to achieve on silicon-on-insulator due to silicon intrinsic properties. In this work, we demonstrate broadband thermally stable tantalum pentoxide microresonators directly coupled to silicon waveguides using a micro-trench co-integration method. The method combines in-foundry silicon processing with a single step backend thin-film deposition. The passive response of the microresonator and its thermal behavior are investigated. We show that the microresonator can operate in the over-coupled regime as well as near the critical coupling point, boasting an extinction ratio over 25 dB with no higher-order mode excitation. The temperature dependent wavelength shift is measured to be as low as 8.9 pm/K and remains below 10 pm/K over a 120 nm bandwidth. (C) 2021 Optical Society of America

Automated summary

Through the investigation of the passive response and thermal behavior of the microresonator, we demonstrate the performance of thermally stable tantalum pentoxide microresonators directly coupled to silicon waveguides, capable of operating in both the over-coupled and near critical coupling regimes with low temperature-dependent wavelength shift.