Abstract

Output unidirectionality is one of the inherent characteristics of an optically pumped far-infrared ring laser (OPFRL).¹ The unidirectionality originates mainly in the asymmetric velocity distribution of off-resonantly pumped molecules and in competition between the two far-IR wave modes counterpropagating in the cavity.² When the two counterpropagating fir waves experience isotropic gain independent of the direction, the cavity-tuning profile of forward output, for example, is just the mirror image of that of the backward output with respect to the line center. The output direction changes at the line center.

© 1995 Optical Society of America