Self-injection locked laser via a hollow-core fiber Fabry-Perot resonator

In a hollow-core fiber (HCF), light propagates through an air/vacuum core rather than a solid material, resulting in a low thermo-optic coefficient and ability to handle high powers. Here, we demonstrate a laser locked to a hollow-core fiber reference, which thanks to the low HCF thermal sensitivity, shows long-term stability an order of magnitude better than compact commercially available low-noise lasers. The laser frequency variation within +/- 600 kHz was measured over 50 h. The stability of our proof-of-concept laser is ensured via a strong self- injection ratio of -15 dB, enabled by the high-power handling and low loss of the hollow-core fiber's resonator. Moreover, our results show appealing performance parameters, including a fractional frequency stability of 4 x 10-13 at 1 s averaging time and a Lorentzian component of the linewidth of 0.2 Hz. Published by Chinese Laser Press under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.