Tunnel junction patterning for controlling optical and current confinement in a vertical-cavity surface-emitting laser

A laser, comprising:

• a quantum well configured to emit light, wherein the quantum well defines a quantum well plane;
• a p-type material proximate the quantum well;
• a first tunnel junction proximate the quantum well along a first optical axis perpendicular to the quantum well plane, wherein the first tunnel junction defines a first optical aperture;
• and
• a second tunnel junction proximate the quantum well along a second optical axis perpendicular to the quantum well plane, wherein the second tunnel junction defines a second optical aperture, and wherein the second tunnel junction is laterally offset from the first tunnel junction in a direction parallel to the quantum well plane;
• wherein each of the first tunnel junction and the second tunnel junction comprises:
• a distinct portion of the p-type material forming a mesa region, wherein the mesa region has a maximum outer dimension, and wherein the mesa region has a first area in a first plane parallel to the quantum well plane;
• and
• an n-type material disposed on the mesa region within the maximum outer dimension, wherein the n-type material has a second area in a second plane parallel to the first plane, and wherein the second area is less than the first area;
• wherein the first tunnel junction increases a first overlap of (i) a first current density through the first optical aperture and (ii) a first optical field of the light through the first optical aperture;
• and
• wherein the second tunnel junction increases a second overlap of (i) a second current density through the second optical aperture and (ii) a second optical field of the light through the second optical aperture.

An array of lasers, comprising:

• a quantum well configured to emit light, wherein the quantum well defines a quantum well plane, and wherein an optical axis is perpendicular to the quantum well plane;
• a p-type material proximate the quantum well;
• and
• for each laser of the array:
• a tunnel junction proximate the quantum well along the optical axis, wherein the tunnel junction defines an optical aperture, wherein the tunnel junction comprises:
• a distinct portion of the p-type material forming a mesa region, wherein the mesa region has a maximum outer dimension, and wherein the mesa region has a first area in a first plane parallel to the quantum well plane;
• and
• an n-type material disposed on the mesa region within the maximum outer dimension, wherein the n-type material has a second area in a second plane parallel to the first plane, and wherein the second area is less than the first area;
• wherein each tunnel junction increases a respective positional overlap of (i) a respective location of maximum current density through the respective optical aperture and (ii) a respective optical field of the light through the respective optical aperture.

A method of manufacturing a laser, the method comprising:

• forming p-type epitaxial layers proximate quantum wells configured to emit light, wherein the quantum wells define a quantum well plane, and wherein an optical axis is perpendicular to the quantum well plane;
• forming p++ type epitaxial layers to form a p++ doped region;
• forming n++ type epitaxial layers to form an n++ doped region;
• etching the n++ doped region and the p++ doped region to form a tunnel junction defining an optical aperture, wherein the tunnel junction comprises:
• p++ doped material, from the p++ doped region, comprising a mesa region having a maximum outer dimension, wherein the mesa region has a first area in a first plane parallel to the quantum well plane;
• and
• n++ doped material, from the n++ doped region, within the maximum outer dimension, wherein the n++ doped material has a second area in a second plane parallel to the first plane, and wherein the second area is less than the first area.