TASK Quarterly (Jan 2011)
WAVEFUNCTION-ENGINEERING OF INTERSUBBAND THz-LASER NANOHETEROINTERFACES
Abstract
A novel THz-luminescence laser nanoheterointerfacial scheme of the intersubband, longer-wavelength limit, mid-infrared functionality type has been designed on the basis of optically-pumped dual-resonant tunnelling of conductivity electrons within an appropriately energetically-determined configuration of five subbands hosted by two communicating asymmetric, approximately rectangular quantum wells (QWs). The employed upper laser-action level is the second excited subband of the nanostructure back, wider QW and is provided with electrons via resonant tunnelling from the first excited subband of the nanostructure front QW populated through remotely ignited optical pumping out of the local fundamental subband. On the other hand, the first excited back-QW subband functions as the lower laser action level, directly delivering the received electrons to the local fundamental subband via a fast vertical longitudinal optical phonon scattering. From there, they are recycled back to the nanostructure front QW fundamental subband by virtue of a second, reverse sense resonanttunnelling-mediated normal charge transport mechanism. A nanophotonics application of the scheme predicts laser operability in the 15-THz range.
