Possibility of a Unidirectional Laser Amplifier Produced by Monochromatic Optical Pumping of a Coupled Doppler-Broadened Transition

Abstract
An optically pumped gas laser amplifier is described which exhibits gain only for waves traveling in a given direction while absorbing waves traveling in the opposite direction. The idea is based on the laser-induced line-narrowing effect in coupled Doppler-broadened transitions for the case of a high-intensity monochromatic pump field.