Unified laser stabilization and isolation on a silicon chip

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 components for high-performance lasers-noise reduction and isolation-can be sourced simultaneously from a single, passive, CMOS-compatible nanophotonic device, eliminating the need to combine incompatible technologies. To realize this, we take advantage of both the long photon lifetime and the non-reciprocal Kerr nonlinearity of a high-quality-factor silicon nitride ring resonator to self-injection lock a semiconductor laser chip while also providing isolation. We also 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. Both laser stabilization and isolation are demonstrated simultaneously by using Kerr nonlinearity in a high-Q silicon nitride ring resonator to self-injection lock a distributed-feedback laser, bringing on-chip lasers closer to real-world fully integrated applications.