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Technique for in situ measurement of free spectral range and transverse mode spacing of optical cavities

Stochino, Alberto and Arai, Koji and Adhikari, Rana X. (2012) Technique for in situ measurement of free spectral range and transverse mode spacing of optical cavities. Applied Optics, 51 (27). pp. 6571-6577. ISSN 0003-6935.

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Length and g-factor are fundamental parameters that characterize optical cavities. We developed a technique to measure these parameters in situ by determining the frequency spacing between the resonances of fundamental and spatial modes of an optical cavity. Two laser beams are injected into the cavity, and their relative frequency is scanned by a phase-lock loop, while the cavity is locked to either laser. The measurement of the amplitude of their beat note in transmission reveals the resonances of the longitudinal and the transverse modes of the cavity and their spacing. This method proves particularly useful to characterize complex optical systems, including very long and/or coupled optical cavities, as in gravitational-wave interferometers. This technique and the results of its application to the coupled cavities of a 40 m-long gravitational-wave interferometer prototype are presented here.

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Adhikari, Rana X.0000-0002-5731-5076
Additional Information:© 2012 Optical Society of America. Received 14 June 2012; accepted 30 July 2012; posted 20 August 2012 (Doc. ID 170533); published 17 September 2012. We thank Yoichi Aso, Robert Ward, and Hiro Yamamoto for illuminating discussions on this technique. We also thank the rest of the 40 m team for building and maintaining the interferometer during the course of this work. The LIGO Observatories were constructed by the California Institute of Technology and the Massachusetts Institute of Technology with funding from the National Science Foundation under cooperative agreement PHY-0757058. This paper has been assigned a LIGO Document Number of P1200048.
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LIGO Laboratory DocumentP1200048
Issue or Number:27
Classification Code:OCIS codes: 120.3180, 120.2230, 120.3940, 350.1270
Record Number:CaltechAUTHORS:20121026-103308783
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35123
Deposited By: Tony Diaz
Deposited On:26 Oct 2012 23:41
Last Modified:03 Oct 2019 04:25

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