High-power cw Nd:YAG lasers pumped with fiber-coupled diode lasers

We report on diode laser side-pumped, cw Nd:YAG rod lasers operating at output powers of several hundred Watts. Applying fiber-coupled diode lasers as pump sources, linear pump power densities of more than 200 W/cm are attainable. A nearly free adjustment of the pump light distribution inside the laseractive medium allows a significant decrease of thermally- induced effects and minimizes aberration-related losses. In multimode operation at 1064 nm, output powers of more than 320 W cw are observed. Applying an improved resonator design, output powers of more than 80 W in TEM00 mode operation are realized with an optical- to-optical efficiency of more than 20%. Frequency conversion into the visible spectral range with optical-to-optical efficiencies (green power to pump power) of 5% is realized by intracavity second harmonic generation in KTP crystals. Thermal properties and laser performance of laser systems excited by fiber-coupled diode lasers will be discussed.