FREE-ELECTRON LASER EXPLOITING A SUPERLATTICE-LIKE MEDIUM

Amplification in free-electron lasers exploiting media with periodical ly modulated refractive indices is studied in the regime of a large mo dulation. The conditions for realization of the large-modulation regim e in a superlattice-like medium are established. The maximized gain, t he corresponding saturation field and efficiency, as well as the optim al electron energy and propagation direction are determined. It is sho wn that the large-modulation regime makes it possible to extend signif icantly the operation frequency domain of the FEL employing a low-rela tivistic electron beam. Relationship with the Cherenkov and stimulated resonance-transition-radiation FELs is discussed. This research is pa rtially supported by RFBR grant 97-02-17783. (C) 1998 Optical Society of America.