Ultrahigh energy gain in small volumes of the active medium in a laser based on an autowave photon-branched chain reaction

The possibility is demonstrated of initiating an autowave photon-branched chain reaction (PBCR) in an originally small focal volume of the laser active medium (H₂—F₂—O₂—He— Al particles) by the external IR radiation focused with a lens. It is shown that the PBCR can spread over the entire active medium of the laser with an unstable telescopic cavity, in the form of self-sustained cylindrical zones of photon branching. The autowave laser-chemical reaction initiated in the lens focus strongly reduces the required energy of the initial input pulse to 0.01 μJ, thereby providing a huge energy gain of ~10¹¹. Because of this ultrahigh gain, a small submicrojoule laser can be used as a master oscillator.