N ovoFEL as Source of Powerful Ultramonochromatic Tunable Terahertz Radiation

Laser nature of a continuous pulse-periodical radiation of the Novosibirsk free-electron laser (NovoFEL) appears in a good coherency of its pulses and very narrow synchronized longitudinal modes. Filtration of one of the modes by a system of three resonance Fabry-Perot interferometers allows to create laser source with monochromaticity which is sufficient for typical high-resolution THz spectroscopy (δf/f ≤ 5·10
^-8
, δf ≤ 0.1 MHz). Features of the source compared to other alternative devices are a wide tuning range (1.5-3 THz) and much more high output power (up to 50-100 mW).