| Paper | Title | Page |
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| TUPA14 | Terahertz Band Free Electron Lasers With Hybrid Bragg Reflectors | 238 |
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Periodical Bragg structures can be considered as an effective way of controlling the electromagnetic energy fluxes and provision of spatial coherence of radiation in the electron devices with oversized interaction space. Advance of FEL with 2D distributed feedback [*] into the terahertz waveband can be achieved basing on a two-mirror hybrid scheme in which a new modification of Bragg reflector exploiting the coupling between the two counter-propagating waves and a cutoff mode is used as an upstream mirror. This reflector provides effective mode selection over the "narrow" transverse coordinate directed between the plates forming planar waveguide. Synchronization of radiation from a sheet electron beam over the "wide" coordinate can be obtained by 2D Bragg structures providing 2D distributed feedback used as a downstream mirror. Both upstream and downstream Bragg reflectors are compatible with intense beam transport. Thus the advantage of suggested scheme against traditional THz band FEL [**] is the possibility of realization of long-pulse (microsecond) generation regimes with high (mulimegawatt) output power level. *Ginzburg N.S., Peskov N.Yu., Sergeev A.S. // Optics Сommun. 1994. V.112. P.151. |