Control of the laser frequency of the Virgo gravitational wave interferometer with an in-loop relative frequency stability of 1.0 x 10^-21 on a 100 ms time scale

Acernese, F.; Alshourbagy, M.; Antonucci, F.; Aoudia, S.; Arun, K. G.; Astone, P.; Ballardin, G.; Barone, F.; Barsuglia, M.; Bauer, T. h. S.; Beker, M.; Bigotta, S.; Birindelli, S.; Bizouard, M. A.; Boccara, C.; Bondu, F.; Bonelli, L.; Bosi, L.; Braccini, S.; Bradaschia, C.; Brillet, A.; Brisson, V.; Bulten, H. J.; Buskulic, D.; Cagnoli, G.; Calloni, E.; Campagna, E.; Canuel, B.; Carbognani, F.; Carbone, L.; Cavalier, F.; Cavalieri, R.; Cella, G.; Chassande Mottin, E.; Chatterji, S.; Chincarini, A.; Cleva, F.; Coccia, E.; Colas, J.; Colla, A.; Colombini, M.; Corda, C.; Corsi, A.; Coulon, J. P.; Cuoco, E.; D'Antonio, S.; Dari, A.; Dattilo, V.; Davier, M.; Day, R.; De Rosa, R.; del Prete, M.; Di Fiore, L.; Di Lieto, A.; Di Paolo Emilio, M.; Di Virgilio, A.; Drago, M.; Fafone, V.; Ferrante, I.; Fidecaro, F.; Fiori, I.; Flaminio, R.; Fournier, J. D.; Franc, J.; Frasca, S.; Frasconi, F.; Freise, A.; Gammaitoni, L.; Garufi, F.; Gemme, G.; Genin, E.; Gennai, A.; Giazotto, A.; Granata, M.; Granata, V.; Greverie, C.; Guidi, GIANLUCA MARIA; Heitmann, H.; Hello, P.; Hild, S.; Huet, D.; La Penna, P.; Leroy, N.; Letendre, N.; Lorenzini, M.; Loriette, V.; Losurdo, G.; Mackowski, J. M.; Majorana, E.; Man, N.; Mantovani, M.; Marchesoni, F.; Marion, F.; Marque, J.; Martelli, Filippo; Masserot, A.; Menzinger, F.; Michel, C.; Milano, L.; Minenkov, Y.; Mohan, M.; Moreau, J.; Morgado, N.; Morgia, A.; Mosca, S.; Mours, B.; Neri, I.; Nocera, F.; Pagliaroli, G.; Palomba, C.; Paoletti, F.; Pardi, S.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Persichetti, G.; Pichot, M.; Piergiovanni, Francesco; Pinard, L.; Poggiani, R.; Prato, M.; Prodi, G. A.; Punturo, M.; Puppo, P.; Rabaste, O.; Rapagnani, P.; Re, V.; Regimbau, T.; Ricci, F.; Robinet, F.; Rocchi, A.; Rolland, L.; Romano, R.; Ruggi, P.; Salemi, F.; Sassolas, B.; Sentenac, D.; Sturani, Riccardo; Swinkels, B.; Terenzi, R.; Toncelli, A.; Tonelli, M.; Tournefier, E.; Travasso, F.; Trummer, J.; Vajente, G.; van den Brand, J. F. J.; van der Putten, S.; Vavoulidis, M.; Vedovato, G.; Verkindt, D.; Vetrano, Flavio; Vicere', Andrea; Vinet, J. Y.; Vocca, H.; Was, M.; Yvert, M.

doi:10.1109/FREQ.2009.5168287

The measurement of the space-time structure variations induced by strong cosmic events (supernovae, coalescing binaries of neutron stars, etc.) requires an oscillator with a relative stability of 10-21 on time scales typically ap100 ms. We demonstrate that the Virgo interferometer with a wavelength of 1.064 degm has a laser frequency with an in-loop stability of 1.0 times 10-21 on a 100 ms time scale, and an in-loop frequency noise of 2 times 10-7 Hz/radic(Hz) at 10 Hz. We show that this fits the specifications. Two references successively stabilize the laser frequency. The first one is a 144 m long suspended cavity; the second one is the common mode of two perpendicular 3 km long Fabry-Perot cavities. The differential mode of the relative length variations of these two optical cavities is the port where we expect the signal for the gravitational waves; this out-of-loop measurement, less sensitive to laser frequency noise, does not show up correlations with the in-loop error signal. This is the best ever performance of short term laser frequency stabilization reported.