| This work summarizes the material and iterative device development approach for long-wavelength InP based diode lasers, emitting at 1.53 microm, that 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: ~ 97% for long-cavity (≥ 2mm) uncoated-facet devices. The characteristic temperature of the slope efficiency, T1, reaches a high value of 323 K. Doping-level optimization over the entire transverse design and the use of the SQW result in low values for the internal loss coefficient: ~ 1.1 cm-1 for long-cavity (≥ 2 mm) uncoated-facet devices and ~ 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 ~ 1W output power from conductively-cooled 100 microm-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 beam-width: 26° full width half maximum (FWHM). |
