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

• Published in: Nature communications Vol. 15; no. 1; pp. 1922 - 8
• Main Authors: Idjadi, Mohamad Hossein, Kim, Kwangwoong, Fontaine, Nicolas K.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-03-2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/624/1020/1093; 639/624/1111/1113; 639/624/399/1097; 639/624/399/1099; Frequency locking; Frequency stabilization; Humanities and Social Sciences; Laser stability; Lasers; Mach-Zehnder interferometers; Miniaturization; Modulation; multidisciplinary; Noise measurement; Noise sensitivity; Photonics; Science; Science (multidisciplinary); Semiconductor lasers; Semiconductors; Silicon
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-46319-3

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
6
. The implemented passive photonic chip occupies an area of 0.456 mm
2
and is integrated on AIM Photonics 100 nm silicon-on-insulator process.
Stable lasers are crucial in many applications like sensing. Here, the authors demonstrate a laser frequency locking method that maintains performance, eliminates modulation, simplifies architecture, and enables miniaturization on a photonic chip.