Several kW-class solid-state lasers at TRW will be described with an emphasis on the performance modeling used to aid development of high brightness operation. Comparisons of results and analysis will be presented for key aspects of high power, diode pumped, Nd:YAG lasers and amplifiers that use zigzag slab configurations to minimize thermal effects. Devices described include multi-kW power oscillators suitable for high power machining, welding, and material processing; and phase conjugated master oscillator/power amplifiers (MOPAs) which provide short pulse, high brightness beams for active tracking, photolithography, or remote sensing. Laboratory measurements are in good agreement with predictions of diode pump profile and absorption efficiency; slab extraction efficiency and thermal load; and slab OPD.