Terahertz quantum-cascade lasers based on an interlaced photon-phonon cascade

A THz (lambdasimilar to80 mum) quantum-cascade laser utilizing alternating photon- and phonon-emitting stages has been developed to achieve efficient extraction of electrons from the lower laser level. Thermal backfilling of electrons is drastically reduced leading to an operation up to 95 K and a weak temperature dependence of the power versus current slope efficiency. The threshold current density is 280 A cm(-2) at 6 K and increases to 580 A cm(-2) at 90 K. Peak output powers of 10 mW at 30 K and 4 mW at 80 K are obtained.