High-selective spatially-extended Bragg resonators implementing three-dimensional distributed feedback for powerful free electron lasers

Novel scheme of Bragg resonators implementing three-dimensional distributed feedback is proposed. The study of their electrodynamic characteristics in the framework of the coupled wave approach has been carried out and high selective properties for the three mode indices have been demonstrated under conditions of substantial oversize. The results of the theoretical analysis are corroborated by the 3D simulations. The prospects of using these resonators in the project of a super-power terahertz-band free electron laser, which is currently being developed at the BINP RAS (Novosibirsk) in collaboration with the IAP RAS (Nizhny Novgorod), are discussed.