A slab laser and its method of use for high power applications including the manufacture of semiconductors and deposition of diamond and/or diamond-like-carbon layers, among other materials. A lamp driven slab design with a face-to-face beam propagation scheme and an end reflection that redirects the amplified radiation back out the same input surface is utilized. A side-to-side amplifier configuration permitting very high average and peak powers having scalability is also disclosed. Cavity filters adjacent to pump lamps convert the normally unusable UV portion of the pump lamp spectrum into light in the absorption band of the slab laser, thereby increasing the overall pump efficiency. The angle of the end reflecting surface is changed to cause the exit beam to be at a different angle than the inlet beam, thereby eliminating the costly need to separate the beams external to the laser with the subsequent loss of power.