Quantum dot vertical cavity surface emitting laser
OwnerXiaodong Huang, Andreas Stintz +4inventors
InventorsXiaodong Huang, Andreas Stintz, Kevin Malloy, Guangtian Liu, Luke Lester, Julian Cheng
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Abstract
A quantum dot vertical cavity surface-emitting laser has a low threshold gain. Top and bottom mirrors have a low mirror loss, with at least one of the mirrors being laterally oxidized to form semiconductor/oxide mirror pairs. In one embodiment, mode control layers reduce the optical field intensity in contact layers, reducing optical absorption. In one embodiment, delamination features are included to inhibit the tendency of laterally oxidized mirrors from delaminating.
Claims39
A quantum dot vertical cavity surface emitting semiconductor laser (VCSEL), comprising:
- a first distributed bragg reflector (DBR) mirror disposed on a substrate layer comprised of a first plurality of mirror pairs with each mirror pair including layers having a step change in indices of refraction;
- a second distributed bragg reflector (DBR) mirror comprised of a second plurality of mirror pairs with each mirror pair including layers having a step change in indices of refraction;
- a semiconductor quantum dot active region disposed between a top of the first DBR mirror and a bottom of the second DBR mirror, the quantum dot active region including a plurality of quantum dots embedded in a plurality of quantum wells disposed proximate at least one antinode of a longitudinal optical mode, the quantum dots having a corresponding optical confinement factor;
- first and second doped semiconductor intracavity contact layers each having a thickness of no more than about half a wavelength disposed between the first and second DBR mirrors positioned and doped to inject electron-hole pairs into the quantum dot active region in response to a drive current;
- the mirror pairs of at least one of the DBR mirrors comprised of a semiconductor layer and an oxidizable semiconductor layer which has been oxidized to form a material with a refractive index substantially lower than the unoxidized semiconductor, increasing the reflectivity of the mirror;
- and
- at least one mode control layer disposed between the top of the first DBR mirror and the bottom of the second DBR mirror forming a refractive index profile to increase optical confinement of the quantum dot active region and reduce optical confinement in the contact layers.
A vertical cavity surface emitting semiconductor laser (VCSEL), comprising:
- a first distributed bragg reflector (DBR) mirror;
- a second distributed bragg reflector (DBR) mirror spaced apart from the first mirror to form a microcavity for a longitudinal optical mode;
- a semiconductor quantum dot active region having a first end and a second end disposed in the microcavity between the mirrors;
- first and second doped semiconductor intracavity contact layers disposed in the microcavity on opposed ends of the quantum dot active region doped to inject electron-hole pairs into the quantum dot active region in response to a drive current;
- at least one mode control layer disposed in the microcavity;
- the at least one mode control layer having a refractive index profile for generating reflections within the microcavity which create a resonance condition that increases optical confinement in the active region and decreases optical loss in contact layers.
A vertical cavity surface emitting laser, comprising:
- first and second distributed bragg reflector (DBR) mirror means for forming an optical cavity between the mirror means having optical feedback;
- quantum dot active means disposed within the optical cavity for providing optical gain responsive to a current;
- intracavity contact layer means for proving current to the quantum dot active means;
- and
- resonant mode control layer means disposed between the mirror means for increasing the optical confinement of the quantum dot active means and reducing the optical intensity in the contact layer means.
A method of forming a vertical cavity surface emitting laser having an oxidized bottom distributed bragg reflector (DBR) mirror with lateral support, comprising:
- etching at least one opening into mirror layers of the bottom DBR mirror, the at least one cavity disposed proximate an outer perimeter of a lasing portion of the bottom DBR mirror with at least one lateral connecting portion of the mirror layers remaining to support the lasing portion of the mirrors;
- and
- laterally oxidizing the mirror layers of the bottom DBR mirror.
A method of forming a vertical cavity surface emitting laser with intracavity contacts from a substrate having a top DBR mirror with DBR mirror layers, a bottom DBR mirror with DBR mirror layers, a top contact layer, an active region, and a bottom contact disposed between the mirrors, the method comprising:
- etching a top mirror mesa to expose the top contact layer outside of a top mirror for the VCSEL;
- masking the top mirror mesa and etching down to the bottom contact layer;
- etching at least one opening into mirror layers of the bottom DBR mirror, the at least one opening disposed proximate an outer perimeter of a lasing portion of the bottom DBR mirror with at least one lateral connecting portion of the layers remaining to support the lasting portion of the mirrors;
- and
- laterally oxidizing the mirror layers of the bottom DBR mirror through the at least one opening.
Dependencies are inferred from the claim text.