Current Excitation Model for Cerenkov Lasers with a Planar Waveguide

A unified theoretical analysis of the spontaneous and stimulated emissions in Cerenkov free-electron lasers (CFELs) with a planar dielectric waveguide is shown. The excitation of the electromagnetic (EM) wave is formulated with current sources of the electron beam. A relativistic classical analysis is applied to this model, where the electron is represented as a spatially localized point particle. The spontaneous emission is evaluated through spatially varying field components associated with the motion of an electron. The stimulated emission is derived on the basis of the modulations of electron velocity and density by the EM field. Interaction regimes induced by the stimulated emission are classified into transition and steady states with the time variation. The effect of electron relaxation is introduced to explain the operation in the steady state. The compatibility of this analysis with already known analyses is also confirmed. (C) 2010 The Japan Society of Applied Physics