Red narrow-linewidth lasing and frequency comb from gain-switched self-injection-locked Fabry-Pérot laser diode

• Published in: Scientific reports Vol. 13; no. 1; p. 9830
• Main Authors: Shitikov, Artem E, Galiev, Ramzil R, Min'kov, Kirill N, Kondratiev, Nikita M, Cordette, Steevy J, Lobanov, Valery E, Bilenko, Igor A
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 17.06.2023; Nature Publishing Group UK; Nature Portfolio
• Subjects: Injection; Injections; Lasers; Lasers, Semiconductor; Light; Spectroscopy
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-023-36229-7

Narrow-linewidth lasers are in extensive demand for numerous cutting-edge applications. Such lasers operating at the visible range are of particular interest. Self-injection locking of a laser diode frequency to a high-Q whispering gallery mode is an effective and universal way to achieve superior laser performance. We demonstrate ultranarrow lasing with less than 10 Hz instantaneous linewidth for 20 [Formula: see text]s averaging time at 638 nm using a Fabry-Pérot laser diode locked to a crystalline MgF[Formula: see text] microresonator. The linewidth measured with a [Formula: see text]-separation line technique that characterizes 10 ms stability is as low as 1.4 kHz. Output power exceeds 80 mW. Demonstrated results are among the best for visible-range lasers in terms of linewidth combined with solid output power. We additionally report the first demonstration of a gain-switched regime for such stabilized Fabry-Pérot laser diode showing a high-contrast visible frequency comb generation. Tunable linespacing from 10 MHz to 3.8 GHz is observed. We demonstrated that the beatnote between the lines has sub-Hz linewidth and experiences spectral purification in the self-injection locking regime. This result might be of special importance for spectroscopy in the visible range.