Patent ID: 7106776

Claim:
An apparatus for amplifying two collinearly propagating beams of monochromatic coherent radiation at optical frequencies v 0 and v′ 0 , comprising: a vessel for containing a gas and maintaining an excitation in the gas volume; wherein intense narrow-band fluorescence is emitted from said excitation at frequencies v 0 and v 0 ′ of allowed optical transitions of constituents of the gas, wherein said optical transitions share a common upper energy level and form a Λ type structure, and wherein one or both lower energy levels are populated in said gas volume, whereby monochromatic laser beams at frequencies v 0 and v 0 ′ propagating collinearly through said gas volume containing vessel nonlinearly convert photons from said fluorescence 11 into photons of said propagating beams, thus amplifying said beams.