Turnkey locking of quantum-dot lasers directly grown on Si

• Published in: Nature photonics Vol. 18; no. 7; pp. 669 - 676
• Main Authors: Dong, Bozhang, Wan, Yating, Chow, Weng W., Shang, Chen, Prokoshin, Artem, Alkhazraji, Emad, Koscica, Rosalyn, Wang, Heming, Bowers, John E.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2024; Nature Publishing Group
• Subjects: 639/624/1020/1093; 639/624/399/1017; 639/624/399/1099; Applied and Technical Physics; Coherence; Feedback; Fiber lasers; Frequency locking; Injection; Lasers; Low cost; Optical gyroscopes; Physics; Physics and Astronomy; Power consumption; Quantum dot lasers; Quantum dots; Quantum Physics; Quantum well lasers; Semiconductor lasers; Silicon; Silicon substrates; Synthesizers
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-024-01413-2

Ultralow-noise laser sources are crucial for a variety of applications, including microwave synthesizers, optical gyroscopes and the manipulation of quantum systems. Silicon photonics has emerged as a promising solution for high-coherence applications due to its ability to reduce the system size, weight, power consumption and cost. Semiconductor lasers based on self-injection locking have achieved fibre laser coherence, but typically require a high-quality-factor external cavity to suppress coherence collapse through frequency-selective feedback. Lasers based on external-cavity locking are a low-cost and turnkey operation option, but their coherence is generally inferior to self-injection locking lasers. In this work, we demonstrate quantum-dot lasers grown directly on Si that achieve self-injection-locking laser coherence under turnkey external-cavity locking. The high-performance quantum-dot laser offers a scalable and low-cost heteroepitaxial integration platform. Moreover, the chaos-free nature of the quantum-dot laser enables a 16 Hz Lorentzian linewidth under external-cavity locking using a low-quality-factor external cavity, and improves the frequency noise by an additional order of magnitude compared with conventional quantum-well lasers. A quantum-dot laser directly grown on silicon that is scalable, low cost with an intrinsic linewidth of 16 Hz when subject to feedback from a low-quality-factor external cavity is reported.