Diode-end-pumped solid state lasers

One way of achieving high-power diode-end pumped lasers is to angularly multiplex several diodes on each end of the laser rod. We have successfully multiplexed four 15 W diode arrays on each end of a 6.3 mm diameter X 7.5 mm long Nd:YAG rod to produce an approximately equals 2 mm diameter pump spot. Higher laser power was achieved by adding a second laser rod pumped at both ends. The addition of the second rod facilitates thermally induced birefringence compensation by introducing a quartz polarization rotator between the rods. In addition, it was necessary to add an aspheric lens to compensate the thermal aberration induced at these high, nonuniform pump powers. With this arrangement, > 90 W has been extracted multimode, and > 60 W in a near-diffraction-limited beam.