Tunable Cerenkov lasers

A Cerenkov laser consists of a mildly to moderately relativistic electron beam, a dielectric resonator, and output coupling components. In the considered configuration of such a device, an electron beam passes over a thin dielectric guide and interacts (primarily) with the axial component of the TM modes of the structure. A bunching of the beam will occur, and, hence, stimulated emission will be produced in those modes which have a phase velocity slightly less than the velocity of the beam. In the selected example, waves are launched from the slab waveguide by a taper. The cavity is then completed by mirrors. An expression is deduced for the gain of a Cerenkov maser. The calculation is facilitated by making a number of simplifying assumptions. The general conclusion which can be drawn from a conducted analysis is that it should be possible to construct tunable Cerenkov lasers in the far-infrared portion of the spectrum.