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, 4.6 - 5.8 THz and 6.1 - 6.4 THz, has been achieved from silicon crystals doped by phosphorus and antimony to around 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 from silicon in the high-frequency bands 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.