VCSEL incorporating a substrate having an aperture
A vertical cavity surface emitting laser (VCSEL) includes a substrate having an aperture that allows light generated in an active layer of the VCSEL to exit the VCSEL after propagation through a first set of semiconductor layers. The VCSEL further includes an opaque bottom layer that blocks light generated in the active layer and propagated through a second set of semiconductor layers. The opaque bottom layer can be attached to a heat sink for heat dissipation thereby allowing the VCSEL to be operated at high power levels. The active layer is sandwiched between the first set of semiconductor layers and the second set of semiconductor layers. Unlike a traditional VCSEL where only certain wavelengths of light can propagate through a solid substrate that is “transparent” to these particular wavelengths, the aperture provided in the substrate of a VCSEL in accordance with the disclosure allows for propagation of many different wavelengths.
1. A vertical cavity surface emitting laser (VCSEL) comprising:
an active layer sandwiched between a first plurality of semiconductor layers and a second plurality of semiconductor layers;
a growth substrate having an aperture that extends from a first major surface of the growth substrate to at least a first major surface of a first semiconductor layer among the first plurality of semiconductor layers, wherein the aperture includes a ledge portion that delineates a first tapered bucket portion of the aperture from a second tapered bucket portion of the aperture; and
an opaque bottom layer configured to block light that is generated in the active layer and propagated through the second plurality of semiconductor layers.
2. The VCSEL of claim 1 , wherein the light generated in the active layer comprises light of a first wavelength and the growth substrate is opaque to light of at least the first wavelength, and further wherein the aperture in the growth substrate is arranged to allow the light generated in the active layer to exit the VCSEL after propagation through the first plurality of semiconductor layers.
3. The VCSEL of claim 1 , wherein the opaque bottom layer is a metal layer.
4. The VCSEL of claim 3 , further comprising a heat sink that is attached to the metal layer for heat dissipation.
5. The VCSEL of claim 1 , wherein the aperture has a first diameter at the first major surface of the growth substrate, the first diameter larger than a second diameter at a second major surface of the growth substrate.
6. The VCSEL of claim 5 , wherein the second major surface of the substrate abuts the first major surface of the first semiconductor layer.
7. The VCSEL of claim 1 further comprising a lens mounted on the ledge portion.
8. The VCSEL of claim 7 , wherein the lens is a ball lens.
9. The VCSEL of claim 1 , wherein the aperture extends from the first major surface of the growth substrate to an interior portion of the first semiconductor layer.
10. The VCSEL of claim 9 , wherein the first semiconductor layer is one of an etch stop layer, a current spreading layer, or a distributed Bragg reflector (DBR) layer.
11. A vertical cavity surface emitting laser (VCSEL) comprising:
an active layer sandwiched between a first plurality of semiconductor layers and a second plurality of semiconductor layers;
a growth substrate having an aperture configured to allow light generated in the active layer to exit the VCSEL after propagation through the first plurality of semiconductor layers, wherein a portion of the aperture is configured to hold a lens through which light generated in the active layer of the VCSEL exits the VCSEL, wherein the portion of the aperture that is configured to hold a lens comprises a ledge portion that delineates a first tapered bucket portion of the aperture from a second tapered bucket portion of the aperture; and
an opaque bottom layer configured to block light that is generated in the active layer and propagated through the second plurality of layers.
12. The VCSEL of claim 11 , wherein the light generated in the active layer comprises light of a first wavelength, and wherein the growth substrate is opaque to light of at least the first wavelength.
13. The VCSEL of claim 12 , wherein the growth substrate comprises GaAs.
14. The VCSEL of claim 11 , wherein the opaque bottom layer is a metal layer, and wherein the aperture has a first diameter at a first major surface of the growth substrate that is larger than a second diameter at a second major surface of the growth substrate, the second major surface of the growth substrate abutting the first plurality of semiconductor layers.
15. The VCSEL of claim 14 , wherein the aperture extends from the first major surface of the growth substrate and through the second major surface of the growth substrate.
16. The VCSEL of claim 15 , wherein the aperture extends through the second major surface of the growth substrate and into at least a portion of a first semiconductor layer among the first plurality of semiconductor layers.
17. The VCSEL of claim 11 , wherein at least a portion of the second tapered bucket portion contains an epoxy material for holding a lens mounted on the ledge portion.
18. A vertical cavity surface emitting laser (VCSEL) comprising:
a growth substrate having a hole extending through the growth substrate, the hole configured to allow light generated in an active layer of the VCSEL to exit the VCSEL, wherein at least a portion of the hole has slanting side walls defined at least in part by a first tapered bucket portion that is delineated from a second tapered bucket portion by a ledge portion, the ledge portion configured to accommodate a lens;
a lens through which light generated in the active layer of the VCSEL exits the VCSEL disposed in the hole; and
an opaque bottom layer located on an opposing side of the VCSEL, the opaque bottom layer configured to block light generated in the active layer of the VCSEL.
19. The VCSEL of claim 18 , wherein the light generated in the active layer comprises light of a first wavelength and the growth substrate is opaque to light of at least the first wavelength.
20. The VCSEL of claim 18 , wherein the hole comprises at least one of a circular section, an oval section, or a quadrilateral section.
21. The VCSEL of claim 18 , wherein at least a portion of the hole has slanting side walls.
22. The VCSEL of claim 18 , wherein the lens is located below a major surface of the growth substrate.
23. The VCSEL of claim 22 , wherein the lens is a ball lens.
24. The VCSEL of claim 18 , wherein the opaque bottom layer is a metal layer, and wherein the hole has a first diameter at a first major surface of the growth substrate that is larger than a second diameter at a second major surface of the growth substrate, the second major surface of the growth substrate located closer to the active layer than the first major surface of the growth substrate.
25. A vertical cavity surface emitting laser (VCSEL) comprising:
an active layer sandwiched between a first plurality of semiconductor layers and a second plurality of semiconductor layers;
a substrate having an aperture that extends from a first major surface of the substrate to at least a first major surface of a first semiconductor layer among the first plurality of semiconductor layers, the aperture including a ledge portion that delineates a first tapered bucket portion of the aperture from a second tapered bucket portion of the aperture; and
an opaque bottom layer configured to block light that is generated in the active layer and propagated through the second plurality of semiconductor layers.