Synchrotron-radiation laser

Abstract

A formulation to characterize stimulated emission of synchrotron radiation is presented, based on simplification of a theory developed by Sokolov and Ternov. It is shown that optical gain may be obtained up to gyration harmonics of the order of the critical harmonic number for spontaneous radiation, 3y\ where / is the relativistic energy factor. Synchrotron-radiation lasers (SRLs) in the infrared and visible portions of the spectrum are shown to be feasible, provided beams with high energy definition are used. SRL gain can exceed free-electron-laser gain for similar beams.PACS numbers: 42.55. Tb, 41.70.+t, 41.80.Ee, 52.75.Ms Recently, convincing experimental evidence [1] showed that strong cooperative effects in the spontaneous synchrotron radiation of gyrating electrons will prevail when the electrons are localized within a spatial bunch that is smaller than the radiation wavelength. As a result, the intensity of the radiation observed was nearly N times that for a single electron, where N is the number of electrons in a bunch. Cooperative radiation effects among electrons which are not localized are described by the phenomena of stimulated emission and absorption, wherein an imposed monochromatic radiation field can excite randomly and widely spaced electrons to either absorb or emit radiation in phase coherence with the imposed radiation. Considerable interest exists in stimulated emission processes involving free electrons, as in gyrotrons [2] and free-electron lasers (FELs) [3] for the generation and amplification of radiation at wavelengths from millimeters to the vacuum ultraviolet.This Letter describes the conditions for obtaining optical gain through stimulated emission of synchrotron radiation from a beam of gyrating electrons in a strong magnetic field. Of course, at the fundamental and first few cyclotron harmonics, such a mechanism has been long