A solid state laser amplifier architecture in which multiple zig-zag slab laser amplifiers (50) are stacked together, side-pumped using a common pump source (52, 54), and cooled with a common cooling system. The stack of zig-zag slabs (50) produces an array of sub-beams (62) that can be combined coherently into a single composite output beam. Variations in pump power absorption through the stack are mitigated by selection of doping levels for the slabs (50). The composite output beam is sufficiently symmetrical to be directed through conventional optics of circular cross section. Multiple stacks may be arranged in a two-dimensional array to obtain even higher output powers.
