VERY HIGH CHARACTERISTIC TEMPERATURE AND CONSTANT DIFFERENTIAL QUANTUM EFFICIENCY 1.3-MU-M GAINASP-INP STRAINED-LAYER QUANTUM-WELL LASERS BY USE OF TEMPERATURE-DEPENDENT REFLECTIVITY (TDR) MIRROR

A very high characteristic temperature T-0 of 150 K (25-70 degrees C) or 450 K (25-50 degrees C) and an almost constant differential quantum efficiency operation in the temperature range of 25-70 degrees C were achieved in 1.3-mu m GaInAsP-InP strained-layer quantum-well (SL-QW) lasers by use of a novel temperature dependent reflectivity (TDR) mirr or composed of multiple quarter-lambda thickness alpha-Si-SiOx dielect ric films with quarter-lambda shift in the vicinity of center portion, The mechanism of high T-0 and constant differential quantum efficienc y were explained using the structural parameters, transparent current density and gain coefficient of a SL-QW laser that are derived experim entally. The effect of TDR mirror was confirmed by measuring the tempe rature dependence of net gain of a SL-QW laser with TDR mirror. It was found that less temperature dependent net gain due to the decrease of mirror loss with temperature played an important role for improving t he temperature characteristics of threshold current, Almost constant d ifferential quantum efficiency over a wide temperature range is attrib uted to the increase of the facet reflectivity with temperature.