Terahertz Stimulated Emission under the Optical Resonant Excitation of Germanium Doped with Shallow Donors

The mechanisms responsible for terahertz stimulated emission under the resonant intracenter excitation of shallow donors in bulk germanium are considered to be population inversion (PI) and electron stimulated Raman scattering (E-SRS). The E-SRS cross section is estimated for the case of the resonant excitation of odd levels of a shallow arsenic donor in bulk germanium. The output intensity under the resonant excitation of arsenic-doped germanium is calculated. It is shown that, at intensities exceeding the E-SRS threshold, there should be competition between mechanisms leading to a decrease in the PI lasing intensity, as can be found from the time dependence of the output intensity.