Efficient diffusive reflector-type diode side-pumped Nd:YAG rod laser with an optical slope efficiency of 55%

We fabricated a compact diode side-pumped Nd:YAG laser with a diffusive reflector, in which the diode laser power is transferred directly into the threefold symmetric diffusive cavity through long narrow slits. With a 7.5% output coupler in a linear resonator, we obtained 62.4-W multimode output power with an optical slope efficiency of 53.4% at a diode power of 182 W, which corresponds to an optical-to-optical efficiency of 34.3%. The optical slope efficiency increased to 55.5% when we used an 11% output coupler. From the leakage power analysis method, the pumping efficiency was measured to be approximately 82%. We discuss the thermal lens and the slope efficiency with respect to absorbed power that is derived from the measured pumping efficiency.