Mode instability and nonlinear superradiance phenomena in open Fabry-Perot cavity

Collective spontaneous emission of discrete modes (i.e., mode superradiance or superfluorescence) in an open Fabry-Perot cavity is considered. The simultaneous emission of counter-propagating coherent pulses is associated with the instability of normal “hot” modes, even in the case of very low, but finite reflection at mirrors, beginning with Rcr 1. A role of nonlinear Bragg backscattering by a self-consistent (λ/2)-lattice of population inversion of active two-level medium is discussed. It is shown that the interference of inhomogeneous counter-propagating waves alters essentially the space-time dynamics of inversion exhaustion and the profile of superradiance pulse, compared with the mean field and the unidirectional models. The novel nonlinear equation of mode superradiance in an open cavity is derived. The approximate analytic solution to the equation is found. Various regimes of superradiance are analyzed on the basis of this solution and compared with numerical simulations.