Design concepts of terahertz quantum cascade lasers: Proposal for terahertz laser efficiency improvements

摘要

Conceptual disadvantages of typical resonant phonon terahertz quantum cascade lasers u0002THz-QCLsu0003nare analyzed. Alternative designs and their combination within a concrete device proposal arendiscussed to improve the QCL performance. The improvements are u00021u0003 indirect pumping of thenupper laser level, u00022u0003 diagonal optical transitions, u00023u0003 complete electron thermalization, and u00024u0003nmaterials with low effective electron masses. The nonequilibrium Green’s function method isnapplied to predict stationary electron transport and optical gain. The proposed THz-QCL shows anhigher optical gain, a lower threshold current, and a higher operation temperature. Alloy disordernscattering can worsen the QCL performance.n© 2010 American Institute of Physics. u0004doi:10.1063/1.3524197