50% continuous-wave wallplug efficiency from 1.53μm-emitting broad-area diode lasers

Long-wavelength InP-based diode lasers emitting at 1.53 mu m have been optimized for maximum continuous-wave (CW) electrical-to-optical power conversion efficiency, so-called wallplug efficiency (WPE). Efficient electron and hole capture into a single-quantum-well (SQW) active region as well as suppression of electron and hole leakage out of the SQW result in high values for the internal differential efficiency: similar to 97% for long-cavity (>= 2 mm) uncoated-facet devices and similar to 85%-89% for short-cavity (1.5 mm) optimized facet-coated devices. The characteristic temperature of the slope efficiency, T-1, reaches a high value of 323 K. Doping-level optimization of the p-cladding layer and the use of the SQW result in low values for the internal loss coefficient: similar to 1.1 cm(-1) for long-cavity (>= 2 mm) uncoated-facet devices and similar to 1.5-2.0 cm(-1) for short-cavity (1.5 mm) optimized facet-coated devices. In turn, a maximum CW WPE value of 50% is achieved at room temperature and similar to 1 W output power from conductively-cooled 100 mu m-wide-aperture devices. The maximum CW power is 2.5 W. One beneficial byproduct of the CW-WPE maximization process is a large transverse spot size which, in turn, provides a very narrow transverse beamwidth: 26 degrees full width half maximum. Reliability tests show no degradation when devices are run CW at high currents (4-5 A) and high temperatures (40-50 degrees C) for over 4000 h, at similar to 2 W output power. (C) 2014 AIP Publishing LLC.