Novel THz sources with profiled focusing field and photonic crystal electrodynamic systems

Methods of the efficiency enhancement of the vacuum terahertz and subterahertz sources based on the resonance of O-type generators with a prolonged interaction (orotron, diffraction radiation oscillator, ledatron, laddertron) are considered. Theoretical analysis is performed on the basis of multidimensional nonlinear self-consistent theory of beam-wave interaction.