Suppression of amplified spontaneous emission in a subpicosecond KrF amplifier laser system using acridine dye

Performance of a two-stage KrF ultrashort-pulse amplifier system using acridine dye as an interstage saturable absorber is studied. Compared to a system employing a spatial filter, the amplified spontaneous emission included within the same solid angle subtended by the output pulse can be reduced by almost an order of magnitude, but at the expense of a 35% reduction in the short-pulse output energy. A criterion is established for the advantageous use of a saturable absorber whose performance is nevertheless degraded by nonsaturable loss.