Quantum-cascade lasers based on a bound-to-continuum transition

A quantum-cascade structure combining the advantages of the three-quantum well and superlattice active regions is demonstrated. In these devices, the emission occurs between a state localized close to the injection barrier and a miniband. A low threshold current density (3.6 kA/cm(2)), large slope efficiency (200 mW/A for 35 periods), and peak power (700 mW) are achieved at 30 degreesC while a peak power of 90 mW is obtained at temperatures as high as 150 degreesC. (C) 2001 American Institute of Physics.