Very low threshold current density GaInAs/AlGaInAs MQW lasers made by phosphorus-free MBE and operating in 1.5–1.6 μm range

Multiquantum-well lasers have been fabricated by molecular beam epitaxy (MBE) in the ‘phosphorus-free’ AlGaInAs/GaInAs system. For the first time, very low current densities were obtained: 940 A/cm2 for a 800 μm-long device at 1.58 μm. The structures used a quaternary alloy for the buffer layer and the quantum well barriers; the best result was obtained from a graded-index waveguide separateconfinement heterostructure.