Fabrication of low-threshold 1.3-μm InAs/InGaAs/GaAs quantum-dot lasers operating at room temperature

We report on the growth, fabrication and characterization of low threshold laser diodes emitting around 1.3 mum. The quantum dot active region was optimised to get the highest photoluminescence emission and the lowest full width at half maximum (FWHM). Broad area laser diodes were processed from different samples containing three layers of InAs quantum dots (QDs), and cleaved at different cavity lengths (L_C ). Electro-luminescence measurements were performed at room temperature under pulsed excitation. The laser diodes operate at room temperature and emit at 1.32 mum, in the low-absorption spectral window for telecom applications. The characteristic temperature T₀ is in the range 60-77 K and the differential quantum efficiency is 53 %. For an infinite cavity length a threshold current density of 8 A/cm² per QD layer was obtained. Lasing from short-cavity diodes (L_C = 750 mum) was also obtained after e-beam evaporation of high-reflection coatings on one edge of the in-plane laser structure