Chip-based laser with 1-hertz integrated linewidth

Published

October 28, 2022

Author(s)

Joel Guo, Charles McLemore, Chao Xiang, Dahyeon Lee, Lue Wu, Warren Jin, Megan Kelleher, Naijun Jin, Lin Chang, Avi Feshali, Mario Paniccia, Peter Rakich, Kerry Vahala, Scott Diddams, Franklyn Quinlan, John Bowers

Abstract

Lasers with hertz-level linewidths on timescales up to seconds are critical for precision metrology, timekeeping, and the manipulation of quantum systems. Such frequency stability typically relies on bulk-optic lasers and reference cavities, where increased size is leveraged to improve noise performance, but with the trade-off of cost, hand assembly, and limited application environments. On the other hand, planar waveguide lasers and cavities exploit the benefits of CMOS scalability, but are fundamentally limited from achieving hertz-level frequency noise at longer times by stochastic noise and thermal sensitivity inherent to the laser and waveguide medium. These physical limits have inhibited the development of integrated lasers with frequency noise required for portable optical clocks that have performance well beyond conventional microwave counterparts. In this work, we break this paradigm to demonstrate a high-coherence, clock-grade laser at 1548 nm with integrated 1 s linewidth of 1.1 Hz and frequency instability less than 10^-14 from 1 ms to 1 s. The corresponding frequency noise at 1 Hz offset is suppressed 11 orders of magnitude from that of the free-running laser down to the cavity thermal noise limit near 1 Hz^2/Hz, decreasing to 2x10^-3 Hz^2/Hz at 10 kHz offset. This record performance leverages wafer-scale lasers and low-loss resonators together with an 8 mL vacuum-gap cavity that employs micro-fabricated mirrors with sub-angstrom roughness to yield an optical Q of 12.6 billion. Significantly, all the critical components are lithographically defined on planar substrates and hold the potential for parallel high-volume manufacturing. This work provides an important advance towards fully integrated and compact lasers with integrated hertz-level linewidths for applications such as portable optical clocks, low-noise RF photonic oscillators, and related communication and navigation systems.

Citation

Science Advances

Pub Type

Journals

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Keywords

Integrated Laser, Chip-based, Fabry-Perot

Citation

Guo, J. , McLemore, C. , Xiang, C. , Lee, D. , Wu, L. , Jin, W. , Kelleher, M. , Jin, N. , Chang, L. , Feshali, A. , Paniccia, M. , Rakich, P. , Vahala, K. , Diddams, S. , Quinlan, F. and Bowers, J. (2022), Chip-based laser with 1-hertz integrated linewidth, Science Advances, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933875 (Accessed July 7, 2024)