Modulation-free laser stabilization technique using integrated cavity-coupled Mach-Zehnder interferometer.

Idjadi, Mohamad Hossein; Kim, Kwangwoong; Fontaine, Nicolas K · Nat Commun · 2024

basic_science · Level V

Where this comes from

Abstract

Stable lasers play a significant role in precision optical systems where an electro-optic laser frequency stabilization system, such as the Pound-Drever-Hall technique, measures laser frequency and actively stabilizes it by comparing it to a frequency reference. Despite their excellent performance, there has been a trade-off between complexity, scalability, and noise measurement sensitivity. Here, we propose and experimentally demonstrate a modulation-free laser stabilization method using an integrated cavity-coupled Mach-Zehnder interferometer as a frequency noise discriminator. The proposed architecture maintains the sensitivity of the Pound-Drever-Hall architecture without the need for any modulation. This significantly simplifies the architecture and makes miniaturization into an integrated photonic platform easier. The implemented chip suppresses the frequency noise of a semiconductor laser by 4 orders-of-magnitude using an on-chip silicon microresonator with a quality factor of 2.5 × 10<sup>6</sup>. The implemented passive photonic chip occupies an area of 0.456 mm<sup>2</sup> and is integrated on AIM Photonics 100 nm silicon-on-insulator process.