Terahertz lasing from silicon by infrared Raman scattering on bismuth centers

Stimulated emission at terahertz frequencies (4.5-5.8 THz) has been realized by electronic Raman scattering of infrared radiation on bismuth donor centers in silicon at low temperatures. The Stokes shift of the observed laser emission is 40.53 meV which corresponds to the bismuth intracenter transition between the 1s(A(1)) ground state and the excited 1s(E) state. The laser has a low optical threshold and the largest frequency coverage in comparison with other Raman silicon lasers based on shallow donor centers. Time-resolved pump spectra enable the separation of donor and Raman lasing.