Cerenkov free electron lasers in the infrared

The Cerenkov free electron laser (CFEL) is evaluated as a potential infraredd radiation source. The model which is evaluated consists of a relativistic electron beam grazing the surface of a single slab dielectric waveguide. Properties of the resonator such as transverse mode spacing, scaling of the output frequency with slab thickness and dielectric constant are examined. The single slab waveguide, with a thickness on the order of the output wavelength, operating in the TM1 mode is found to be a suitable choice as a resonator for a CFEL. The small signal gain of the device is computed for the single particle interaction mechanism for the cases of an infinite and zero magnetic guide field. An examination of the expression for the gain shows it to be independent of the dielectric material for operation in the infrared regime. Although a low dielectric constant (episilon approximately 2-4) is desirable as it provides for thicker waveguides capable of handling higher power outputs. In the mm regime the gain of the CFEL is enhanced by using materials with moderately high dielectric constants (episilon approximately 10-25).