Abstract

GEO600, an interferometric gravitational-wave detector with an arm length of 600m, is currently being built in northern Germany close to Hannover [1]. Once finished, GEO600 will be a 4-fold delayline Michelson-interferometer giving a round trip optical length of 2400m. The modulation, needed to keep the output port at a dark fringe, will be done by external modulation in an additional Mach-Zehnder interferometer. The light source, a monolithic diode pumped ND-YAG ring laser (MISER) as the master oscillator and a slab amplifier, will give a power of about 10W. Power recycling increases the. power inside the interferometer to a level of about 10kW. The use of both power and signal recycling will give a sensitivity of the same order of magnitude as the first stages of the other large-scale gravitational-wave detectors LIGO (the American project) and VIRGO (the French/Italian collaboration) currently under construction [2, 3]. High signal-recycling factors allow to increase the sensitivity at a chosen frequency while reducing the bandwidth of the detector. This gives an advantage over broadband detectors in detecting periodic sources such as pulsars.

© 1996 IEEE