Thermo-optic locking of a semiconductor laser to a microcavity resonance

TL;DR

This paper demonstrates a stable, long-term thermo-optic locking method for semiconductor lasers to microresonators, achieving linewidth narrowing without electronic control, promising ultralow linewidth on-chip lasers.

Contribution

The study introduces a novel thermo-optic locking technique that maintains laser resonance for over twelve hours without electronic feedback, utilizing optical feedback and thermal effects.

Findings

Lock maintained for over twelve hours without electronic control

Optical feedback narrows laser linewidth

Potential for ultralow linewidth on-chip lasers

Abstract

We experimentally demonstrate thermo-optic locking of a semiconductor laser to an integrated toroidal optical microresonator. The lock is maintained for time periods exceeding twelve hours, without requiring any electronic control systems. Fast control is achieved by optical feedback induced by scattering centers within the microresonator, with thermal locking due to optical heating maintaining constructive interference between the cavity and the laser. Furthermore, the optical feedback acts to narrow the laser linewidth, with ultra high quality microtoroid resonances offering the potential for ultralow linewidth on-chip lasers.