NONLINEAR BRAGG SCATTERING AND MODE SUPERRADIANCE IN AN OPEN FABRY-PEROT CAVITY

Mode superradiance (i.e. superfluorescence) in an open Fabry-Perot resonator is characterised by simultaneous emission of counterpropagarting coherent pulses even at very low (but finite) values of the mirrors reflection coefficient, beginning from R(cr) much-less-than 1. It is postulated that for any value of the resonator Q-factor, even when R much-greater-than R(cr) or R approximately 1, a self-matched lambda/2 grating of the populations inversion in a two-level medium does not result in significant Bragg reflection which would exceed the reflection from the mirrors. A consistent allowance for the interference of inhomogeneous conterruning waves alters significantly the spatial and temporal dynamics of depletion of the population inversion and, consequently, changes greatly the profile of collective spontaneous radiation pulses, compared with the predictions of the mean field and unidirectional superradiance theories. A new nonlinear equation for superradiance in an open resonator is derived.