Organic dye lasers with intracavity absorption - Rate equation models

The characteristics of CW organic dye lasers with intracavity absorption have been discussed by taking account of spatial relaxation as well as mode competition. Spatial inhomogeneity is introduced to account for the multimode coexistence based on the idea that one active molecule gives its energy to the strongest mode in its neighborhood, and never to more than one mode at a time. Individual modes are assumed to have their own reservoirs of the active molecules distributed around the loops of the standing waves along the cavity axis. The reservoirs are connected with one another through diffusion-like spatial relaxation. Spectral homogeneity and mode competition are also preserved by a common reservoir shared by all the modes. A comparison is made with the conventional single-path absorption method, under the same conditions, for estimating the absorption enhancement factor. Absorption is greatly enhanced for weak pumpings, wide band operation, strong mode competition, and large spatial relaxation.