Terahertz Lasing at Roomtemperature: Numerical Study of a Vertical-Emitting Quantum Cascade Laser Based on a Quantum Dot Superlattice

We investigate room temperature lasing of terahertz quantum cascade lasers using quantum dot chains as active material suitable for wireless communication and imaging technologies. Bandstructure calculations for such extended systems of coupled quantum dots are made possible by a novel ‘linear combination of quantum dot orbitals’–method, based on single quantum dot wavefunctions. Our results demonstrate strong vertical-emission of coupled quantum dots, reduced phonon coupling and in-plane scattering, enabling room-temperature lasing with significantly reduced threshold current densities.