Transient THz stimulated emission from silicon pumped by FELs

Transient-type stimulated emission in the terahertz frequency range has been achieved from silicon crystals doped by phosphorus and bismuth donors under optical excitation by a few picosecond-long pulses generated by the infrared free electron lasers, FELIX and CLIO. The lasing emission occurs due to a population inversion based mechanism for different interpulse intervals (40 ns, 20 ns, 16 ns, 1 ns) and due to stimulated Raman scattering for interpulse intervals of 1 ns.