Laser development and stabilization

The high-power laser plays a key role in laser interferometric gravitational wave detectors, both on the ground as well as in space. All first generation gravitational wave detectors are limited in the higher Fourier frequency range by quantum noise on the light. In future detectors this noise source can be reduced by either use of non-classical techniques or by a higher optical power circulating in the interferometer. The circulating light power will be limited to about 1 MW due to thermo-optical limitiations. Lasers with several hundreds Watts of power will be needed to achieve such a high circulating power. In addition to high power, the laser has to provide a high spatial mode purity and low free-running frequency and intensity noise to allow stabilization methods to reduce the fluctuations to a level which does not limit the sensitivity of the detector.