Stimulated Emission from Donor Transitions in Silicon

The observation of far-infrared stimulated emission from shallow donor transitions in silicon is reported. Lasing with a wavelength of $59\mu \mathrm{m}$ due to the neutral donor intracenter ${2p}_0\to 1s\left(E\right)$ transition in Si:P pumped by ${\mathrm{CO}}_2$ laser radiation is obtained. Populations of $D^0$ and $D^{-}$ center states and the balance of the radiation absorption and amplification are theoretically analyzed.