Study of Raman free-electron laser oscillator with Bragg reflection resonators

A high-gain Raman free-electron laser oscillator is realized by using a Bragg reflection resonator with a limited pulse duration of the electron beam (0.4 MeV/800 A. 60 ns). The practical design of the Bragg reflectors is introduced. A concept of hybrid oscillator configuration which combines the high gain of a superradiant amplifier with the narrow bandwidth of a conventional oscillator (Fabry-Perot resonator) is put forward and is confirmed by experimental results. It shows that 14 MW peak power at 7.7 mm wavelength (bandwidth Delta lambda / lambda <5%) with a 4.4% electronic efficiency is produced. The measured fundamental wavelength of the radiation spectrum is compared with the result of calculations.<
>