Mechanism Of Terahertz Lasing In SiGeSi Quantum Wells

Blom et al. [189] presented a theoretical calculation, which showed the formation of resonant states, and explained the origin of the observed temperature dependence of the dc conductivity under low bias voltage. Thus, it was shown that the mechanism of terahertz (THz) lasing is population inversion of the resonant state with respect to the localized impurity state. This is the same mechanism of lasing as in uniaxially stressed p-Ge THz lasers.

In an early experiment [190] published in 1992, THz radiation was observed from bulk p-Ge under uniaxial stress and a dc electric field, both applied along the same crystal axis. Eight years later measurements of the radiation spectrum characterized the observed radiation as pulse mode lasing under pumping of a strong electric field [191]. A theoretical explanation of the lasing phenomenon followed almost immediately [192], which proved the formation of resonant states as the required mechanism for achieving population inversion. Shortly thereafter, a tunable continuous

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