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Phonon-Limited-Linewidth of Brillouin Lasers at Cryogenic Temperatures

Suh, Myoung-Gyun and Yang, Qi-Fan and Vahala, Kerry J. (2017) Phonon-Limited-Linewidth of Brillouin Lasers at Cryogenic Temperatures. Physical Review Letters, 119 (14). Art. No. 143901. ISSN 0031-9007. doi:10.1103/PhysRevLett.119.143901.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Suh, Myoung-Gyun0000-0002-9527-0585
Yang, Qi-Fan0000-0002-7036-1712
Vahala, Kerry J.0000-0003-1783-1380
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.
Group:Kavli Nanoscience Institute
Funding AgencyGrant Number
Defense Advanced Research Projects Agency (DARPA)W31P4Q-14-1-0001
Kavli Nanoscience InstituteUNSPECIFIED
Issue or Number:14
Record Number:CaltechAUTHORS:20170807-104744818
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:79843
Deposited By: Ruth Sustaita
Deposited On:07 Aug 2017 17:58
Last Modified:15 Nov 2021 17:50

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