Low resistance intracavity-contacted oxide-aperture VCSELs

The authors study, analytically and experimentally, the extrinsic series resistance in intracavity-contacted vertical-cavity surface-emitting lasers (VCSEL's). Low resistance, low threshold-current, intracavity-contacted VCSELs are fabricated, with resistances ranging from 355 /spl Omega/ for 4-μm square apertures to 80 /spl Omega/ for 12-μm square apertures and threshold voltages as low as 1.35 V. To the best of our knowledge, these are the lowest values reported for this type of VCSEL. The threshold currents range from 270 μA for 4 μm×4 μm apertures to 850 μA for 12 ×12 μm. From a comparison of the resistance as a function of oxide aperture radius, the measured data follows closely with the calculated data, demonstrating the validity of the derived expressions for series resistance.