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Optically pumped terahertz semiconductor bulk lasers

The principles of stimulated emission for the terahertz frequency range from shallow impurity centers in bulk semiconductors are discussed. Evidence of stimulated emission from group V donors embedded in silicon (P, Sb, Bi) as well as spontaneous emission from Li acceptor in monocrystalline ZnSe under excitation by CO2 laser radiation at low temperatures is demonstrated. The temporal behavior and the emission spectra of the lasers are presented.