A high-power, diode-laser-pumped, solid state laser for precision interferometry

Interferometric gravitational-wave detectors require an efficient laser that provides many tens of watts of cw power in a diffraction-limited, single-frequency mode. The fiber-coupled, diode-laser-pumped, Nd:YAG laser described in this thesis is designed to address both the power and stability requirements of these detectors.; The laser design includes twenty five 10 watt, fiber-coupled diode lasers as the pump source, Nd:YAG as the laser host and a zigzag slab geometry to minimize thermal effects. A novel Teflon protective coating allows direct water cooling. The 1.7 mm x 1.8 mm x 58.9 mm slab dimensions are chosen to achieve a high gain and minimize the chance of stress fracture. The measured small signal gain of the Nd:YAG slab pumped with 235 watts is e{dollar}sp{lcub}0.9{rcub}{dollar} The stress depolarization of the slab at this pump level is below 0.5%.; Optimum performance of the zigzag slab design requires uniform pumping and cooling the TIR surfaces of the slab while insulating all other surfaces. At a full pump power, the laser head showed less than 1 wave of distortion in a Helium-Neon interferometer. Multimode output of 72 watts cw was achieved with a threshold of 30 watts and a slope efficiency of 36%. TEM{dollar}sb{lcub}00{rcub}{dollar} mode output of 40 watts cw was achieved with a threshold of 30 watts and a slope efficiency of 22%. The M{dollar}sp2{dollar} parameter of the beam was below 1.3 and the output was polarized with a ratio of 100:1. Reliable single frequency operation was achieved by using the technique of injection locking and over 20 watts of single frequency output was obtained. Finally, scaling of this laser was demonstrated. With a dual-head cavity, a multimode output of 96 watts cw was obtained at a pump power of 437 watts. In an amplifier configuration, the second gain element provided a single pass amplification of 60%, from 40 watts to 64 watts output. The power level, stability, and scalability of diode-laser-pumped, Nd:YAG lasers make it the preferred choice for interferometric gravitational-wave detection.