Patent ID: 7826506

Claim:
A VCSEL comprising a substrate and an epitaxial structure, wherein the epitaxial structure comprises: a bottom DBR mirror disposed on the substrate wherein the bottom mirror is essentially undoped; a periodically doped first conduction layer region of a first conductivity type, the doped first conduction layer region coupled to the bottom DBR mirror, the doped first conduction layer region including a heavily doped layer at a location where the optical electric field is at about a minimum; an active layer disposed on the periodically doped first conduction layer region that contains quantum wells; a periodically doped second conduction layer region of a second conductivity type, the doped second conduction layer region coupled to the active layer, the doped second conduction layer region including a heavily doped layer at a location where the optical electric field is at about a minimum; an aperture formed in the epitaxial structure above the quantum wells and below the second conduction layer region, wherein the aperture is defined by an oxidized AlGaAs layer; a ramp layer positioned between the aperture and the second conduction layer region, the ramp layer including a ramp of aluminum in a composition of the ramp layer, wherein the ramp layer, the heavily doped layer and the oxidized AlGaAs layer are within a single null of a standing wave of the VCSEL; a top mirror coupled to the periodically doped second conduction layer region, wherein the top mirror is essentially undoped and includes a plurality of layers of AlGaAs having an aluminum content in a range from 70% to 100%, the top mirror forming a mesa structure; and a protective oxide layer surrounding the top mirror to protect at least a portion the top mirror from being oxidized during a wet oxidation step.