Unified laser stabilization and isolation on a silicon chip

TL;DR

This paper introduces a CMOS-compatible silicon nitride nanophotonic device that simultaneously stabilizes and isolates a semiconductor laser on a chip, overcoming previous limitations and enabling reliable, integrated laser systems.

Contribution

The authors demonstrate a novel integrated device that combines laser noise reduction and isolation using a high-Q silicon nitride resonator, a significant step towards fully integrated photonic systems.

Findings

Achieved self-injection locking and isolation on a single chip

Overcame power regime limitations of existing on-chip lasers

Demonstrated turnkey reliable integrated laser system

Abstract

Rapid progress in photonics has led to an explosion of integrated devices that promise to deliver the same performance as table-top technology at the nanoscale; heralding the next generation of optical communications, sensing and metrology, and quantum technologies. However, the challenge of co-integrating the multiple components of high-performance laser systems has left application of these nanoscale devices thwarted by bulky laser sources that are orders of magnitude larger than the devices themselves. Here we show that the two main ingredients for high-performance lasers -- noise reduction and isolation -- currently requiring serial combination of incompatible technologies, can be sourced simultaneously from a single, passive, CMOS-compatible nanophotonic device. To do this, we take advantage of both the long photon lifetime and the nonreciprocal Kerr nonlinearity of a high quality factor silicon nitride ring resonator to self-injection lock a semiconductor laser chip while also providing isolation. Additionally, we identify a previously unappreciated power regime limitation of current on-chip laser architectures which our system overcomes. Using our device, which we term a unified laser stabilizer, we demonstrate an on-chip integrated laser system with built-in isolation and noise reduction that operates with turnkey reliability. This approach departs from efforts to directly miniaturize and integrate traditional laser system components and serves to bridge the gap to fully integrated optical technologies.