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Featured researches published by A. Villar.


Classical and Quantum Gravity | 2007

Titania-doped tantala/silica coatings for gravitational-wave detection

G. M. Harry; M. Abernathy; Andres E Becerra-Toledo; H. Armandula; Eric D. Black; Kate Dooley; Matt Eichenfield; Chinyere Nwabugwu; A. Villar; D. R. M. Crooks; G. Cagnoli; J. Hough; Colin R How; Ian MacLaren; P. G. Murray; S. Reid; S. Rowan; P. Sneddon; Martin M. Fejer; R. Route; S. Penn; P. Ganau; Jean-Marie Mackowski; C. Michel; L. Pinard; A. Remillieux

Reducing thermal noise from optical coatings is crucial to reaching the required sensitivity in next generation interferometric gravitational-wave detectors. Here we show that adding TiO2 to Ta2O5 in Ta2O5/SiO2 coatings reduces the internal friction and in addition present data confirming it reduces thermal noise. We also show that TiO2-doped Ta2O5/SiO2 coatings are close to satisfying the optical absorption requirements of second generation gravitational-wave detectors.


Physical Review D | 2010

Measurement of thermal noise in multilayer coatings with optimized layer thickness

A. Villar; Eric D. Black; R. DeSalvo; Kenneth G. Libbrecht; C. Michel; N. Morgado; L. Pinard; I. M. Pinto; V. Pierro; Vincenzo Galdi; M. Principe; Ilaria Taurasi

A standard quarter-wavelength multilayer optical coating will produce the highest reflectivity for a given number of coating layers, but in general it will not yield the lowest thermal noise for a prescribed reflectivity. Coatings with the layer thicknesses optimized to minimize thermal noise could be useful in future generation interferometric gravitational wave detectors where coating thermal noise is expected to limit the sensitivity of the instrument. We present the results of direct measurements of the thermal noise of a standard quarter-wavelength coating and a low noise optimized coating. The measurements indicate a reduction in thermal noise in line with modeling predictions.


Physics Letters A | 2004

Direct observation of broadband coating thermal noise in a suspended interferometer

Eric D. Black; A. Villar; Kyle Barbary; Adam Bushmaker; J. Heefner; Seiji Kawamura; F. Kawazoe; Luca Matone; Sharon Meidt; S. R. Rao; Kevin Schulz; Michael Zhang; Kenneth G. Libbrecht

Abstract We have directly observed broadband thermal noise in silica/tantala coatings in a high-sensitivity Fabry–Perot interferometer. Our result agrees well with the prediction based on indirect, ring-down measurements of coating mechanical loss, validating that method as a tool for the development of advanced interferometric gravitational-wave detectors.


Physical Review D | 2015

Material loss angles from direct measurements of broadband thermal noise

M. Principe; I. M. Pinto; V. Pierro; R. DeSalvo; Ilaria Taurasi; A. Villar; Eric D. Black; Kenneth G. Libbrecht; C. Michel; N. Morgado; L. Pinard

We estimate the loss angles of the materials currently used in the highly reflective test-mass coatings of interferometric detectors of gravitational waves, namely Silica, Tantala, and Ti-doped Tantala, from direct measurement of coating thermal noise in an optical interferometer testbench, the Caltech TNI. We also present a simple predictive theory for the material properties of amorphous glassy oxide mixtures, which gives results in good agreement with our measurements on Ti-doped Tantala. Alternative measurement methods and results are reviewed, and some critical issues are discussed.


Physical Review Letters | 2004

Thermoelastic-Damping Noise from Sapphire Mirrors in a Fundamental-Noise-Limited Interferometer

Eric D. Black; A. Villar; Kenneth G. Libbrecht

We report the first high-precision interferometer using large sapphire mirrors, and we present the first direct, broadband measurements of the fundamental thermal noise in these mirrors. Our results agree well with the thermoelastic-damping noise predictions of Braginsky, et al. and Cerdonio et al., which have been used to predict the astrophysical reach of advanced interferometric gravitational wave detectors.


Physical Review D | 2008

All-sky search for periodic gravitational waves in LIGO S4 data

B. Abbott; R. Abbott; R. Adhikari; J. Agresti; Stuart B. Anderson; M. Araya; H. Armandula; S. Ballmer; B. Barish; B. Bhawal; G. Billingsley; E. Black; K. Blackburn; Rolf Bork; V. Boschi; D. A. Brown; D. Busby; L. Cardenas; C. Cepeda; S. Chatterji; D. C. Coyne; T. D. Creighton; Erika D'Ambrosio; R. DeSalvo; R. W P Drever; R. J. Dupuis; P. Ehrens; E. Espinoza; T. Etzel; M. Evans


Archive | 2006

Thermal noise in sapphire mirrors in a high-sensitivity interferometer

E. Black; A. Villar; Kenneth G. Libbrecht

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Eric D. Black

California Institute of Technology

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Kenneth G. Libbrecht

California Institute of Technology

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C. Michel

Centre national de la recherche scientifique

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L. Pinard

Centre national de la recherche scientifique

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E. Black

California Institute of Technology

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