Study on correlation between rayleigh scattering, absorption and inhomogeneous birefringence in large-size single crystal sapphire

Full text: Advanced laser interferometric gravitational wave detectors require very high laser power to minimize the photon shot noise. The use of a high power requires extremely low loss optical materials. Sapphire is one of the most promising test mass materials for advanced laser interferometric gravitational wave detectors. However, it is difficult for manufacturers to grow large-size high-quality samples. Due to point defects and inhomogeneity in test masses, the interaction between high-optical power and defect test mass materials is usually resulted in various thermal effects that can lead to damage, introducing excess noise and thus reducing the sensitivity. It is essential to evaluated high-grade large sapphire test mass samples to ensure that an adequate high level of optical performance is achieved. Optical properties such as absorption, Rayleigh scattering, and, in the case of sapphire, inhomogeneous birefringence are related to impurity and defects in the material, and thus are not independent process. Here we present the study of correlation between Rayleigh scattering, absorption and inhomogeneous birefringence in bulk sapphire samples. Copyright (2005) Australian Institute of Physics