Bistability in the operation of an organic dye laser

The threshold behavior of both longitudinally and transversely pumped organic dye lasers has been analyzed theoretically in terms of a rate-equation approach. In both cases, softmode or hard-mode, onset of laser operation can occur, provided typical laser parameters (cavity length and cross sections for stimulated emission and reabsorption) exceed theoretically predicted critical values. Hardmode behavior, corresponding to a first-order phase transition in Landau's theory, includes ranges of bistability of the laser pump power, whose magnitude can be estimated from the set of laser parameters.