This program of research by the Byer group will directly support the LIGO project through laser development; studies of thermal effects from high power operation; frequency doubling using nonlinear crystals. Laser stabilization, and laser reliability will also be investigated. The work on laser development will complete the construction and testing of a 13-W diode-laser-pumped Nd:YAG laser. Studies of thermal effects will include both numerical modeling of these in interferometers, as well as measurements of scatter, absorption, and stress-induced birefringence in optical components. Research on frequency doubling will investigate efficient doubling using materials such as LBO, magnesium oxide-doped lithium niobate, and periodically poled lithium niobate.