Abstract

A diffraction grating rhomb remains the most viable candidate for sideband suppression and optical beam outcoupling in rf-driven free-electron lasers. A pefect rhomb is defined by the positioning of two equal period diffraction gratings so that the grating surfaces and grooves are parallel. The sideband light components, generated in the wiggler section of the laser, interfere with the energy extracted from the electron beam and reduce laser efficiency. Since the group travel time of light in free space through the rhomb is an increasing function of wavelength, the transmit time of the sideband components will differ from the fundamental and thus eliminate the temporal (and spatial) overlap between these components and the electron beam pulse in the wiggler.

© 1988 Optical Society of America