Vertical cavity surface emitting laser having multiple top-side contacts

1. 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.

2. The VCSEL of claim 1 , wherein the top mirror comprises alternating layers of GaAs and AlGaAs.

3. The VCSEL of claim 1 , further comprising a ramp layer, the ramp layer including AlGaAs where the aluminum content ramps between at least 50% and 71%.

4. The VCSEL of claim 1 , wherein the top mirror comprises alternating layers of GaAs and AlAs.

5. The VCSEL of claim 1 , wherein the protective oxide layer has at least a portion which is about 3 λ/8.

6. The VCSEL of claim 1 , wherein the first and/or the second conduction layer region comprises layers that are doped at between about 5×10 19 /cm 3 to 1×10 20 /cm 3 at about the minimum of the optical electric field and less than 1×10 18 /cm 3 away from the minimum of the optical electric field.

7. The VCSEL of claim 1 , further comprising an intracavity contact coupled to the second conduction layer region.

8. The VCSEL of claim 7 , wherein the intracavity contact comprises TiAu.

9. The VCSEL of claim 7 , wherein the top mirror forms at least a portion of a mesa and the intracavity contact metal is coupled to the sides of the mesa.

10. The VCSEL of claim 1 , further comprising a second intracavity contact coupled to the first conduction layer region.

11. The VCSEL of claim 1 , wherein the VCSEL is designed to operate at a wavelength of at least 1260 nm.

12. A VCSEL as in claim 1 , wherein the protective oxide layer is a layer of silicon dioxide surrounding the AlGaAs layers.

13. A VCSEL as in claim 1 , wherein the oxidized layer is less than 30 nm.

14. A VCSEL as in claim 1 , wherein the second conduction layer region is less than 40 nm.