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

Record low threshold current densities have been achieved in InGaAs/InGaAsP step graded index separate confinement (GRIN SCH) quantum well lasers emitting close to 1.50microns. Single (SQW) and multiple (MQW) quantum well lasers with 300-500microns long cavities had threshold current density as low as 1.9 and 0.9 KA/cm sup 2 , respectively. In longer cavity devices, threshold current densities as low as 450 A/cm sup 2 have been measured. These lasers show no significant change in threshold current density with well thickness varying from 5-25 nm which demonstrates the effectiveness of the graded index in the carrier capture process. Buried heterostructure GRIN SCH-SQW and MQW with active layer widths of around 2microns show threshold currents of 15 and 9 mA, respectively.