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Phonon-Pumped Terahertz Gain In N-Type Gaas/Algaas Superlattices, Greg Sun, Richard A. Soref
Phonon-Pumped Terahertz Gain In N-Type Gaas/Algaas Superlattices, Greg Sun, Richard A. Soref
Physics Faculty Publications
Local population inversion and far-IR gain are proposed and theoretically analyzed for an unbiased n-doped GaAs/Al0.15Ga0.85As superlattice pumped solely by phonons. The lasing transition occurs at the Brillouin zone boundary of the superlattice wave vector kzbetween the two conduction minibands CB1 and CB2 of the opposite curvature in kzspace. The proposed waveguided structure is contacted above and below by heat sinks at 300 K and 77 K, respectively. Atop the superlattice, a heat buffer layer confines longitudinal optical phonons for enhanced optical-phonon pumping of CB1 electrons. A gain of 345 cm …
Sige/Si Thz Laser Based On Transitions Between Inverted Mass Light-Hole And Heavy-Hole Subbands, L. Friedman, Greg Sun, Richard A. Soref
Sige/Si Thz Laser Based On Transitions Between Inverted Mass Light-Hole And Heavy-Hole Subbands, L. Friedman, Greg Sun, Richard A. Soref
Physics Faculty Publications
We have investigated a SiGe/Si quantum-well laser based on transitions between the light-hole and heavy-hole subbands. The lasing occurs in the region of k space where the dispersion of ground-state light-hole subband is so nonparabolic that its effective mass is inverted. This kind of lasing mechanism makes total population inversion between the two subbands unnecessary. The laser structure can be electrically pumped through tunneling in a quantum cascade scheme. Optical gain as high as 172/cm at the wavelength of 50 μm can be achieved at the temperature of liquid nitrogen, even when the population of the upper laser subband is …