GAIN SATURATION IN SINGLE-PASS AND DOUBLE-PASS OPTICALLY PUMPED LASER-AMPLIFIERS

The operation of an optically pumped laser amplifier has been studied for two different geometries: the single pass and the double pass conf igurations. The influence of superflourescent emission, self-absorptio n of the laser emission and pump beam depletion have been included. Ou r results indicate that for a longitudinally pumped amplifier configur ation, a multipass geometry is a disadvantage since it results in high er loss through enhanced superfluorescent emission and self absorption . Also, more passes do not result in increased pin length because of a substantial depletion in the pump beam energy. Thus, only for low las er input signals is the stage pin for the double pass amplifier higher than that for the single pass amplifier.