Very closely spaced quadspot native-oxide confined 780-nm semiconductor lasers

We describe the fabrication and characteristics of 7-μm spaced quadspot, independently addressable 785-nm native-oxide confined ridge waveguide laser diodes. The devices are fabricated from an Al/sub 0.1/Ga/sub 0.9/As-Al/sub 0.4/Ga/sub 0.6/As-Al/sub 0.5/In/sub 0.5/P quantum-well separate confinement heterostructure laser structure. Wet oxidation of the p-Al/sub 0.5/In/sub 0.5/P cladding layer is used to form a native oxide for not only ridge waveguide confinement, but also electrical insulation to allow electrical connection to laser stripes. These diodes show excellent performance: uniform threshold currents below 8 mA and differential quantum efficiencies over 35%/facet. The diodes show crosstalk less than 5%.