New principals to generate stimulated emission in terahertz frequency range from silicon doped by shallow donor centers have been demonstrated. Lasing in the frequency bands of 1.2 – 1.8 THz; 2.5 – 3.4 THz, 5.0 – 5.2 THz and 6.1 – 6.4 THz, has been achieved from silicon crystals doped by phosphorus to ∼1015 cm−3, under optical pumping by radiation of mid-infrared free electron laser at cryogenic temperatures. Analysis of the data shows that the emission in high-frequency band corresponds to Stokes-shifted Raman-type lasing, the shift is determined by the 1s(E)-1s(A1) donor electronic resonance. The low-frequency bands indicate on high-order nonlinear frequency conversion processes accompanied by high-energy intervalley phonons of host lattice.
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