Exciton-population inversion and terahertz gain in semiconductors excited to resonance.
The buildup of exciton populations in resonantly laser excited semiconductors is studied microscopically. For excitation around the 2s-exciton resonance, it is shown that polarization with a strict s-type radial symmetry can be efficiently converted into an incoherent p-type population. As a consequence, inversion between the 2p and 1s exciton states can be obtained leading to the appearance of significant terahertz gain.
Kira
M
M
Fachbereich Physik and Material Sciences Center, Philipps Universität, Renthof 5, 35032 Marburg, Germany.
Koch
S W
SW