Very low threshold InGaAs/InGaAsP graded index separate confinement heterostructure quantum well lasers grown by atmospheric pressure metalorganic vapor phase epitaxy

Abstract

Record low threshold current densities have been achieved in InGaAs/InGaAsP step graded index sep[AV:arate confinement (GRIN SCH) quantum well lasers emitting close to 1.50 μm. Single (SQW) and multiple (MQW) quantum well lasers with 300–500 μm long cavities had threshold current densities as low as 1.9 and 0.9 kA/cm², respectively. In longer cavity devices, threshold current densities as low as 750 and 450 A/cm² have been measured in SQW and MQW lasers, respectively. These lasers show no significant change in threshold current density with well thicknesses varying from 5 to 25 nm which demonstrate the effectiveness of the graded index in the carrier capture process. Buried‐heterostructure GRIN SCH SQW and MQW with active layer widths of ∼2 μm show threshold currents of 15 and 9 mA, respectively.