Indirectly Pumped 3.7 THz InGaAs/InAlAs Quantum-Cascade Lasers Grown by Metal-Organic Vapor-Phase Epitaxy

Device-performances of 3.7 THz indirect-pumping quantumcascade lasers are demonstrated in an InGaAs/InAlAs material system grown by metal-organic vapor-phase epitaxy. The lasers show a low threshold-current-density of ~420 A/cm and a peak output power of ~8 mW at 7 K, no sign of parasitic currents with recourse to well-designed coupled-well injectors in the indirect pump scheme, and a maximum operating temperature of Tmax~100 K. The observed roll-over of output intensities in current ranges below maximum currents and limitation of Tmax are discussed with a model for electron-gas heating in injectors. Possible ways toward elevation of Tmax are suggested. ©2012 Optical Society of America OCIS codes: (140.3070) Infrared and far-infrared lasers; (140.5965) Semiconductor lasers, quantum cascade; (230.5590) Quantum-well devices. References and links 1. R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. 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