Radiation pressure induced instabilities in laser interferometric detectors of gravitational waves

The large scale interferometric gravitational wave detectors consist of Fab ry-Perot cavities operating at very high powers ranging from tens of kW to MW for next generations. The high powers may result in several nonlinear ef fects which would affect the performance of the detector. Tn this, paper, w e investigate the effects of radial;ion pressure, which tend to displace th e mirrors from their resonant position resulting in the detuning of the cav ity. Mic observe a remarkable effect: namely, that the freely hanging mirro rs gain energy continuously and swing with increasing amplitude. It is foun d that the "time delay", that is, the time taken for the field to adjust to its instantaneous equilibrium value, when the mirrors are in motion, is re sponsible for this effect. This effect is likely to be important in the opt imal operation of the full-scale interferometers such as VIRGO and LIGO.