High-coherence hybrid-integrated 780 nm source by self-injection-locked second-harmonic generation in a high-Q silicon-nitride resonator

• DOI: 10.1364/optica.498391
• Publication Date: 2023-08-30T18:00:06Z
• Authors: Bohan Li; Zhiquan Yuan; Warren Jin; Lue Wu; Joel Guo; Qing-Xin Ji; Avi Feshali; Mario Paniccia; John E. Bowers; Kerry J. Vahala
• Keywords: Atomic and Molecular Physics; Electronic; FOS: Physical sciences; Optical and Magnetic Materials; and Optics; 7. Clean energy; 530; Physics - Optics; Optics (physics.optics)

Visible, high-coherence optical sources are important to a wide range of applications spanning spectroscopy to precision timing. Integration of these sources on a semiconductor chip is a necessary step if the systems that use these devices are to be made compact, portable, and low power. Here, by self-injection-locking a 1560 nm distributed feedback semiconductor laser to a high-Q silicon-nitride resonator, a high-coherence 780 nm second-harmonic signal is generated via the photogalvanic-induced second-order nonlinearity. A record-low frequency noise floor of 4Hz2/Hz is achieved for the 780 nm emission. The approach can potentially generate signals over a wide range of visible and near-visible bands, and thereby help transition many table-top systems into a fieldable form.