Ultrahigh level of frequency stabilisation of an injection locked Nd : YAGlaser with relevance to gravitational wave detection

We report on measurements of the frequency noise of a highly stabilised inj ection locked Nd:YAG laser. We use a nested loop frequency stabilisation sc heme to achieve a loop gain of similar to1 x 10(6) at Fourier frequencies a round 1 kHz with frequency actuation applied only to the master oscillator. A frequency noise level of similar to2 x 10(-5) HzHz(-1/2) was measured fo r the master laser around this frequency using an independent, narrow line width, suspended analyser cavity. Furthermore we demonstrate that the frequ ency noise performance of the injection locked slave laser is identical to that of the master oscillator to this level. This performance is very close to the frequency noise specification for gravitational wave detection by G EO 600. (C) 2000 Elsevier Science B.V. All rights reserved.