Free-electron laser exploiting a superlattice-like medium

Abstract

Amplification in free-electron lasers exploiting media with periodically modulated refractive indices is studied in the regime of a large modulation. The conditions for realization of the large-modulation regime in a superlattice-like medium are established. The maximized gain, the corresponding saturation field and efficiency, as well as the optimal electron energy and propagation direction are determined. It is shown that the large-modulation regime makes it possible to extend significantly the operation frequency domain of the FEL employing a low-relativistic electron beam. Relationship with the Cherenkov and stimulated resonance-transition-radiation FELs is discussed. This research is partially supported by RFBR grant 97-02-17783.

Diffusive radiation in the infrared region

“…A short-wavelength radiation can be generated by a FEL using either a highenergy (multi-GeV) electron beam or undulators with a short period. One way of constructing short-period undulator-like media can be related with using media with a periodically modulated refractive index (MPMRI) [1][2][3]. MPMRI can be considered as a kind of a volume diffraction grating.…”

“…The following two types of MPMRI can be used: (1) a gas-plasma medium with periodically varied density or degree of ionization [1] and (2) a spatially periodical solid-state superlattice-like (SLL) structure, which can be composed, e.g. of a series of layers of different materials with different refractive indices (see [2] and references therein). Note that a closely related but simpler effect of a stimulated trans ition emission was observed experimentally [4] in a scheme similar to that suggested in [1,2] but without media modulation.…”

“…of a series of layers of different materials with different refractive indices (see [2] and references therein). Note that a closely related but simpler effect of a stimulated trans ition emission was observed experimentally [4] in a scheme similar to that suggested in [1,2] but without media modulation. Free electron lasers and strophotrons [2] can be used as broadly tunable and very powerful sources of infrared light.…”