Kazuki Kuba

Improvement of slab-laser beam divergence by using an off-axis unstable–stable resonator

Reduction of the beam divergence of a solid-state slab-geometry laser by using an off-axis unstable–stable resonator is described. The resonator acts as an off-axis negative-branch unstable resonator in the slab-width direction. This resonator configuration yields a small beam divergence of 2.5 mrad in the unstable-resonator direction at an average output power of 120 W. This improvement in beam quality is achieved without appreciable loss of efficiency.

1.4-kW Nd:YAG slab laser with a diffusive closed-coupled pump cavity

A high-power high-efficiency Nd:YAG slab laser with lamp pumping is developed by use of a novel diffusive-closed coupled lamp pump cavity. In cw-mode operation, 1.45 kW of output power is obtained with a slope efficiency of 5.0%. In pulsed-mode operation (50 pulses/s, 25% pulse duty), 1.4 kW of output power is obtained with a slope efficiency of 4.3%. The output power per unit volume is 45 W/cm(3). To our knowledge, these output powers and the power per unit volume are the highest obtained for the single-head Nd:YAG slab laser with lamp pumping.