Highly efficient neodymium:yttrium aluminum garnet laser end pumped by a semiconductor laser array

In recent experiments, 80-mW cw power in a single mode has been achieved from a neodymium: yttrium aluminum garnet (Nd:YAG) laser with only 1 W of electrical power input to a single semiconductor laser array pump. This corresponds to an overall efficiency of 8%, the highest reported cw efficiency for a Nd:YAG laser. A tightly focused semiconductor laser end pump configuration is used to achieve high pumping intensities (on the order of 1 kW/cm2), which in turn causes the photon to photon conversion efficiency to approach the quantum efficiency (76% for Nd:YAG at 1.06 μm pumped at 0.810 μm). This is achieved despite the dual-lobed nature of the pump. Through the use of simple beam-combining schemes (e.g., polarization coupling and multireflection point pumping), output powers over 1 W and overall electrical to optical efficiencies as high as 10% are expected.