Phonon-Limited-Linewidth of Brillouin Lasers at Cryogenic Temperatures
- Creators
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Suh, Myoung-Gyun
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Yang, Qi-Fan
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Vahala, Kerry J.
Abstract
Laser linewidth is of central importance in spectroscopy, frequency metrology, and all applications of lasers requiring high coherence. It is also of fundamental importance, because the Schawlow-Townes laser linewidth limit is of quantum origin. Recently, a theory of stimulated Brillouin laser (SBL) linewidth has been reported. While the SBL linewidth formula exhibits power and optical Q factor dependences that are identical to the Schawlow-Townes formula, a source of noise not present in conventional lasers, phonon occupancy of the Brillouin mechanical mode is predicted to be the dominant SBL linewidth contribution. Moreover, the quantum limit of the SBL linewidth is predicted to be twice the Schawlow-Townes limit on account of phonon participation. To help confirm this theory the SBL fundamental linewidth is measured at cryogenic temperatures in a silica microresonator. Its temperature dependence and the SBL linewidth theory are combined to predict the number of thermomechanical quanta at three temperatures. The result agrees with the Bose-Einstein phonon occupancy of the microwave-rate Brillouin mode in support of the SBL linewidth theory prediction.
Additional Information
© 2017 American Physical Society. Received 12 June 2017; published 2 October 2017. The authors thank Andrey Matsko for helpful discussions. This research was supported by the DARPA PULSE program (Grant No. W31P4Q-14-1-0001), the Kavli Nanoscience Institute, and by NASA (Award No. JPL.1459106). M.-G. S. and Q.-F. Y. contributed equally to this work.Attached Files
Published - PhysRevLett.119.143901.pdf
Submitted - 1706.03359.pdf
Supplemental Material - supplement-phonon-limited_1_.pdf
Files
Additional details
- Eprint ID
- 79843
- Resolver ID
- CaltechAUTHORS:20170807-104744818
- Defense Advanced Research Projects Agency (DARPA)
- W31P4Q-14-1-0001
- Kavli Nanoscience Institute
- NASA
- JPL.1459106
- Created
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2017-08-07Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field
- Caltech groups
- Kavli Nanoscience Institute