High-power (1.4 W) AlGaInP graded-index separate confinement heterostructure visible (λ∼658 nm) laser

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Abstract
Pulsed operation of an AlGaInP graded-index separate confinement heterostructure laser grown by organometallic vapor phase epitaxy is reported. The laser active region consists of a single 100 Å Ga0.5In0.5P quantum well and 1600 Å graded index regions on both sides of the well. The graded index regions were produced by lattice-matched graded composition (AlyGa1−y)0.5In0.5P quaternary alloys. This structure reduces the broad-area threshold current compared to a double heterostructure laser, with pulsed thresholds as low as 1050 A/cm2. Total pulsed power of 1.4 W at 658 nm is available from an 80 μm×300 μm mesa-stripe laser. A differential quantum efficiency of ∼56% is measured. By examining the cavity length dependence of the threshold current density and quantum efficiency, it is apparent that the quantum well gain has not saturated in these structures. This suggests that devices containing a thinner single quantum well active region may result in a further reduction in threshold current density for visible lasers.