Three-mode parametric instabilities may compromise stable operation of gravitational wave detectors. Instabilities manifest as varying radiation pressure distributions, derived from beating between two optical modes, exciting mirror acoustic modes in Fabry-Pérot cavities. Here we report the first demonstration of radiation pressure driving of ultrasonic acoustic modes via pairs of optical modes in gravitational wave type optical cavities. In this experiment ∼0.4 W of TEM01 mode and ∼1 kW of TEM00 mode circulated inside the cavity, an ∼181.6 kHz excitation was observed with amplitude ∼5×10-13 m. The results verify the driving force term in the parametric instability feedback model (Braginsky et al., 2001) . The interaction parametric gain was (3.8±0.5)×10-3 and mass-ratio scaled opto-acoustic overlap 2.7±0.4. © 2013 Elsevier B.V.
|Journal||Physics Letters, Section A: General, Atomic and Solid State Physics|
|Publication status||Published - 2013|