M modes in a diode side-pumped Nd:glass slab laser

We have operated a pulsed Nd:glass slab laser in a hemiconfocal cavity with beam stops to produce a multibounce beam in the shape of the letter M. This configuration permits the extraction of diffraction-limited beams from a large volume of the slab. The output of the slab was in four beams, and the optical slope efficiency was 14%.