Stringent upper-limit on monolithic optical cavity length noise for gravitational wave detectors
Résumé
The Advanced Virgo detector uses two monolithic optical cavities at its output port to suppress higher order modes and radio frequency side-bands from the carrier light used for gravitational wave detection. These two cavities in series form the output mode cleaner. We present a measured upper limit on the length noise of these cavities that is consistent with the thermo-refractive noise prediction of 8×10−16m/Hz1/2 at 15Hz. The cavity length is controlled using Peltier cells and piezo-electric actuators to maintain resonance on the incoming light. A length lock precision of 3.5×10−13m is achieved. These two results are combined to demonstrate that the length noise of the output mode cleaner is at least a factor 10 below other expected noise sources in the Advanced Virgo detector design configuration.