Continuous coupling of electron beam to a thin dielectric slab waveguide yields monochromatic Cherenkov diffraction radiation

A scheme for generation of monochromatic Cherenkov radiation in a thin dielectric layer is proposed. The electrons travel in vacuum parallel to a dielectric, exciting a single synchronous electromagnetic waveguide mode. The proposed scheme is studied quantitatively for near-infrared radiation in silicon induced by a 100-keV electron beam, using time-domain and frequency-domain numerical simulations, with material absorption and dispersion taken into account. This method of radiation generation can be scaled from ultraviolet to terahertz radiation by changing the thickness of the dielectric layer and choosing a material with low loss at the desired wavelength. Comparison with conventional Cherenkov Radiation and Cherenkov Diffraction Radiation is also presented.