A diode-bar side-pumped waveguide laser with an extended stable cavity for spatial mode control

We describe the use of an extended stable cavity to control the output spatial mode of a diode-bar side-pumped slab waveguide laser. The active medium consists of a Nd:YAG core with a one-dimensional double-clad guiding structure. The device gives >10 W output power with a 56% slope efficiency for multi-mode operation, which is reduced to 33% for the best output beam quality parameters (M2 values) of 2.8×1.1. The prospects for obtaining higher efficiencies and scaling to larger average powers are discussed.