Diffractive focusing of an input pulse and giant energy gain in a laser based on an auto-wave photon-branched network

The wave approximation is used to analyse the energy parameters and the spa tiotemporal behaviour of the electromagnetic field in a pulsed chemical las er based on a photon-branched chain reaction in an unstable telescopic cavi ty with an input coupling aperture through which the reaction is initiated by IR radiation in a gaseous disperse medium composed of H-2, F-2, O-2, He, and Al particles. It is shown that diffractive multifocal focusing of a pl ane input wave, ensuring minimisation of the initially excited volume and a correspondingly strong reduction (down to microjoules) of the required inp ut pulse energy, occurs in the range of small input aperture diameters d(0) = (3-30)lambda. A giant energy gain of similar to 3 x 10(9) can be reached as a result of this optical effect and also because of auto-wave propagati on of a photon-branched chain reaction throughout the whole volume of the l aser. This giant gain makes it possible to construct a self-contained laser with a kilojoule output energy, which can be initiated by microjoule input pulses.