Direction Characteristics of an Optically Pumped Far Infrared Ring Laser Emission

Direction characteristics of emission have been observed on an optically pumped far-infrared (FIR) ring laser. The FIR output from a CH3OH laser is emitted in only a direction depending on the tuning of the FIR cavity. This phenomenon is analyzed theoretically by a 3-level laser model supported by a well-known 2-mode laser theory. The model explains the directionality of the FIR output for significant pump detunings and for small pump powers. The model also predicts that bidirectional emission occurs for large pump powers or for small detunings of the pump transition