# Bridging ultra-high-Q devices and photonic circuits

## TL;DR

This paper introduces an integrated ridge resonator with a record Q factor over 200 million, bridging the gap between ultra-high-Q microcavities and integrated photonic circuits, enabling advanced nanophotonic devices.

## Contribution

The development of a record-high Q integrated ridge resonator that combines ultra-low-loss performance with flexible design, facilitating the integration of microcavities into photonic circuits.

## Key findings

- Achieved a Q factor over 200 million in an integrated device.
- Demonstrated soliton sources with electronic repetition rates.
- Showcased high-coherence Brillouin lasers on a single platform.

## Abstract

Optical microcavities are essential in numerous technologies and scientific disciplines. However, their application in many areas relies exclusively upon discrete microcavities in order to satisfy challenging combinations of ultra-low-loss performance (high cavity-Q-factor) and cavity design requirements. Indeed, finding a microfabrication bridge connecting ultra-high-Q device functions with micro and nanophotonic circuits has been a long-term priority of the microcavity field. Here, an integrated ridge resonator having a record Q factor over 200 million is presented. Its ultra-low-loss and flexible cavity design brings performance that has been the exclusive domain of discrete silica and crytalline microcavity devices to integrated systems. Two distinctly different devices are demonstrated: soliton sources with electronic repetition rates and high-coherence Brillouin lasers. This multi-device capability and performance from a single integrated cavity platform represents a critical advance for future nanophotonic circuits and systems.