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A simple method for reducing the threshold current of vertical cavity surface-emitting lasers (VCSELs) is described. The approach modifies the top surface of the laser into a dome shape by chemical etching. This reduces the reflectance of the top mirror over an approximately annular region, thereby reducing the lasing area compared to the contact area in a controlled manner. A sevenfold reduction in threshold current over equivalent conventional VCSELs is demonstrated for a nonoptimized device that maintains a similar threshold current density. © 1995 John Wiley & Sons, Inc.

The authors report what they believe to be the first successful fabrication of an InGaAs/GaAs vertical-cavity surface emitting laser (VCSEL) using optically transparent indium-tin-oxide (ITO) ohmic contacts to p- and n-type regions of the laser. Threshold current densities J/sub th/ are similar to those lasers fabricated from the same wafer using conventional ohmic contacts.

Optically transparent low resistivity Indium Tin Oxide (ITO) ohmic contacts to both n- and p-type GaAs have been successfully investigated. Contacts are featureless and may be used in surface emitting lasers and other optoelectronic devices. >

Ring-waveguide and pill-box structures down to 12 ?m in diameter, made in GaAs/GaAlAs heterostructure material, have been designed with output stripe waveguides coupled to the rings via Y-junctions. The waveguides were defined by reactive ion etching, although the inner boundaries of some of the ring waveguides relied on stress and carrier confinement. Lasing has been observed with pulsed drive current, and has been shown to correspond to resonances in the rings, although other resonances have been observed in some of the structures. This type of structure is suitable for use as a light source in monolithic integrated optics.