In this report, we present data on an InGaAs/GaAs strained single quantum well laser with the lowest reported threshold current density to date, namely 44 A cm−2 for a 3 mm cavity length. This was grown by solid-source molecular-beam epitaxy with the arsenic dimer, As2. The structure is that of a graded-index, separate-confinement heterostructure with a single strained InGaAs quantum well, sandwiched between GaAs barrier layers and AlGaAs cladding layers. The wavelength of the lasers was around 985 nm, and the internal efficiency and losses were 69% and 0.70 cm−1, respectively. In addition, data on the uniformity of our lasers, which are grown on rotating 2 in substrates (1 in = 2.54 cm), show drops in photoluminescence emission wavelength and layer thickness of less than 4 nm and 4%, respectively, from the centre to the edge of the wafer and very little compositional change.
