Metamorphic 1.5 µm-range quantum dot lasers on a GaAs substrate

Abstract

1.5 µm-range laser diodes based on InAs/InGaAs quantum dots (QDs) grown on metamorphic (In, Ga, Al)As layers, which were previously deposited on GaAs substrates using a defect reduction technique (DRT), are studied. More than 7 W total output power operation in the pulsed mode is shown in broad area lasers. It is shown that the narrow stripe lasers operate in the continuous wave (CW) and the single transverse mode at current densities up to 22 kA cm−2 without significant degradation. CW output power in excess of 220 mW at 10 °C heat sink temperature is demonstrated. 800 mW single-mode output power in the pulsed regime is obtained. It is also shown that the lasers demonstrate the absence of beam filamentation up to the highest current densities studied. First studies on the dynamics of the lasers show a modulation bandwidth of ∼3 GHz, limited by device heating. Eye diagrams at 2.5 Gbit s−1 and room temperature (RT) have been performed. Aging tests demonstrate >800 h of CW operation at ∼50 mW at 10 °C heat sink temperature and >200 h at 20 °C heat sink temperature without decrease in optical output power. The results indicate the high potential of metamorphic growth using the DRT for practical applications, such as 1500 nm GaAs vertical cavity surface emitting lasers (VCSELs).