Emitting at 1.3μm, the micro laser was tested under continuous-wave lasing at up to 100°C, making it very promising for integration into compact optical communication systems.
Their paper "1.3 μm submilliamp threshold quantum dot micro-lasers on Si" published in the Optica journal reveals a novel GaAs-on-Si heterogeneous growth strategy which confines dislocations and growth defects and allows for direct growth on silicon with no germanium buffer layer or substrate miscut. This was combined with a quantum dot (QD)-based active medium, known to effectively alleviate the negative influence of dislocations and surface recombination arising from lattice-mismatched growth and device fabrication.
First, the researchers etched V-grooves along the  direction on a (001) silicon substrate, which they filled with an array of GaAs in-plane nanowires grown directly inside the silicon V-grooves by selective-area metal-organic chemical vapor deposition.
Then further GaAs was grown including 15 periods of Al0.3Ga0.7As∕GaAs (5/5nm) superlattice for annihilating the threading dislocations. Eventually the GaAs nanowires were coalesced into a 1.5μm-thick continuous and smooth surface, on top of which a GaAs∕AlxGa1−xAs graded-index separate-confinement laser heterostructure was grown in a molecular beam epitaxy system. This included seven InAs/InGaAs quantum dot-in-a-well layers incorporated in the laser active region, with a quantum dot density approaching 6×1010 cm−2.
The paper reports that the 4.1% lattice mismatch between GaAs and silicon was mostly accommodated by the formation of a few nanometer-thick stacking faults in the V -grooved structure, enabling the fabrication of a defect-free GaAs laser with performances comparable to devices built on a native GaAs substrate.