Unidirectional coupling of radiation out of a resonator-free laser

A new system for the excitation of a resonator-free laser is considered. In contrast to the familiar regime of a wave traveling along the optic axis, the point at which the scanning occurs is not the point of local deposition of the pump energy, but the point where the threshold conditions are satisfied. When the phase matching conditions are obeyed by the distribution of the pump power along the optic axis, the reverse laser flux may be suppressed and the radiation energy is then coupled out only in one direction. The law of longitudinal modulation of the pump power is then satisfied in the laser. A report is given of an experimental study of a resonator-free Ar–N₂ laser excited by a high-intensity proton beam. The reverse flux is reported to be reduced more than threefold. The main radiation flux is observed in the predicted direction.