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High precision optical cavity length and width measurements using double modulation

Staley, A. and Hoak, D. and Effler, A. and Izumi, K. and Dwyer, S. and Kawabe, K. and King, E. J. and Rakhmanov, M. and Savage, R. L. and Sigg, D. (2015) High precision optical cavity length and width measurements using double modulation. Optics Express, 23 (15). pp. 19417-19431. ISSN 1094-4087.

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We use doubly phase modulated light to measure both the length and the linewidth of an optical resonator with high precision. The first modulation is at RF frequencies and is set near a multiple of the free spectral range, whereas the second modulation is at audio frequencies to eliminate offset errors at DC. The light in transmission or in reflection of the optical resonator is demodulated while sweeping the RF frequency over the optical resonance. We derive expressions for the demodulated power in transmission, and show that the zero crossings of the demodulated signal in transmission serve as a precise measure of the cavity linewidth at half maximum intensity. We demonstrate the technique on two resonant cavities, with lengths 16 m and a 4 km, and achieve an absolute length accuracy as low as 70 ppb. The cavity width for the 16 m cavity was determined with an accuracy of approximately 6000 ppm. Through an analysis of the systematic errors we show that this result could be substantially improved with the reduction of technical sources of uncertainty.

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Additional Information:© 2015 OSA. Received 26 May 2015; revised 2 Jul 2015; accepted 7 Jul 2015; published 17 Jul 2015. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation, and operates under cooperative agreement PHY-0757058. Advanced LIGO was built under award PHY-0823459. AS would like to thank Columbia University in the City of New York for its support. M. R. acknowledges partial support from NSF-HRD 1242090 and DoD W911NF-13-1-0140. This paper has been assigned LIGO Document No. LIGO-P1400184.
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Army Research Office (ARO)W911NF-13-1-0140
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Other Numbering System NameOther Numbering System ID
LIGO DocumentLIGO-P1400184
Issue or Number:15
Classification Code:OCIS codes: (120.5060) Phase modulation; (140.4780) Optical resonators; (120.3940) Metrology; (120.2230) Fabry-Perot; (040.2840) Heterodyne
Record Number:CaltechAUTHORS:20151001-115911997
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Official Citation:A. Staley, D. Hoak, A. Effler, K. Izumi, S. Dwyer, K. Kawabe, E. King, M. Rakhmanov, R. Savage, and D. Sigg, "High precision optical cavity length and width measurements using double modulation," Opt. Express 23, 19417-19431 (2015)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60692
Deposited By: Tony Diaz
Deposited On:01 Oct 2015 20:03
Last Modified:03 Oct 2019 08:59

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