Extraction-controlled quantum cascade lasers

A simple two-well design for terahertz quantum cascade lasers is proposed which is based on scattering injection and the efficient extraction of electrons from the lower laser level by resonant tunneling. In contrast to existing designs this extraction also controls the positive differential conductivity. The device is analyzed by calculations based on nonequilibrium Green’s functions, which predict lasing operation well above 200 K at a frequency of 2.8 THz.