Abstract

We have developed a thin, modular, and stackable diode package to produce a flat diode pump aperture of high brightness. We have incorporated microchannel cooling technology into the package to also permit high average power operation. The packages are 2 cm wide and mount 1.8 cm of diode bar. The packages can be stacked with a pitch of 5.5 packages per centimeter. We are using these packages to achieve high average power diode pumped solid-state laser operation. A face pumped slab geometry has been chosen to take advantage of the large face area available for simple diode pumping. The slab is 90 mm long with a laser aperture of 4 mm by 18 mm. The front end of the slab is antireflection coated, while the back face is coated for high reflection. A folded zigzag optical path is used to hold the wavefront distortion low under average power loading. The zigzag laser cavity is formed by two external mirrors and the high reflector on the back face of the YAG slab. In our initial studies, the external mirrors are each 20 cm from the transmitting crystal face. The folded zigzag optical path traces a three diamond shaped pattern in the slab. All of the external mirrors used have a radius of curvature of 75 cm. The slab’s two pump faces are pumped by a diode stack of 40 packages each. Average Nd: YAG laser power output of 275 w has been achieved at 2.5-kHz repetition rates.

© 1991 Optical Society of America