Lasers with beam shape and beam direction modification
View Patent ↗A reflective surface is disclosed in conjunction with a semiconductor laser to shape a laser beam and modify a direction of the laser beam. The reflective surface may be formed on a structure disposed adjacent to a laser structure to allow high coupling of laser light to, for example, a silicon photonics chip or an optical fiber.
1. A semiconductor laser, comprising:
a substrate;
a laser structure on the substrate, the laser structure comprising an active region that emits light;
an etched facet formed in the laser structure;
a reflective surface disposed apart from the etched facet to receive and reflect light emitted from the active region through a single medium, the reflective surface having a curvature; and
a flat patio surface formed on the substrate and disposed between and adjacent to both the etched facet and the reflective surface, the flat patio surface separating the etched facet and the reflective surface directly beneath the active region by a first distance, the flat patio surface forming a plane that runs parallel to a center plane of the active region, the plane of the flat patio surface and the center plane of the active region separated by a second distance, the center plane of the active region and a plane parallel to the center plane of the active region and touching a top of the reflective surface separated by a third distance, wherein the first distance is greater than the second distance and approximately equal to the third distance.
2. The semiconductor laser of claim 1 , wherein the laser structure is an epitaxial laser structure formed on the substrate.
3. The semiconductor laser of claim 2 , wherein the laser structure further comprises:
a lower cladding layer disposed between the substrate and the active region; and
an upper cladding layer disposed adjacent the active region opposite the substrate.
4. The semiconductor laser of claim 3 , wherein the laser structure further comprises:
a contact layer disposed adjacent the upper cladding layer opposite the active region.
5. The semiconductor laser of claim 4 , wherein the reflective surface is disposed apart from the etched facet such that the top of the reflective surface extends above a top of the contact layer.
6. The semiconductor laser of claim 1 , wherein the reflective surface is disposed apart from the etched facet such that the top of the reflective surface extends above a top of the active layer.
7. The semiconductor laser of claim 1 , wherein the reflective surface is part of a reflective structure on the substrate.
8. The semiconductor laser of claim 7 , wherein the reflective structure is an epitaxial structure formed on the substrate.
9. The semiconductor laser of claim 8 , wherein the reflective structure is an epitaxial layered structure formed on the substrate.
10. The semiconductor laser of claim 1 , wherein the reflective surface is coated with a reflective material.
11. The semiconductor laser of claim 10 , wherein the reflective material is gold.
12. The semiconductor laser of claim 11 , wherein the reflective surface is coated with titanium and gold.
13. The semiconductor laser of claim 1 , wherein the laser structure is a ridge laser.
14. The semiconductor laser of claim 13 , wherein the ridge laser comprises a ridge that expands as it approaches the etched facet.
15. The semiconductor laser of claim 1 , wherein the curvature of the reflective surface is concave.
16. The semiconductor laser of claim 15 , wherein the reflective surface is disposed at an approximate 45° angle between a plane intersecting two ends of the reflective surface and a plane of the etched facet.
17. The semiconductor laser of claim 16 , wherein the reflective surface reflects the light in a direction substantially parallel to the plane of the etched facet.
18. The semiconductor laser of claim 15 , wherein the reflective surface is disposed at an approximate 45° angle between a plane intersecting two ends of the reflective surface and a plane normal to the plane of the flat patio surface.
19. The semiconductor laser of claim 18 , wherein the reflective surface reflects the light in a direction substantially parallel to the plane normal to the plane of the flat patio surface.
20. The semiconductor laser of claim 1 , further comprising at least one sidewall disposed between the etched facet and the reflective surface to modify a direction of the light emitted from the active region.
21. The semiconductor laser of claim 1 , wherein the reflective surface is configured to reflect the light at an angle other than 90° from a direction at which the light is received at the reflective surface.
22. The semiconductor laser of claim 21 , wherein the angle is away from the laser structure.
23. The semiconductor laser of claim 21 , wherein the angle is towards the laser structure.
24. The semiconductor laser of claim 7 , wherein the reflective structure does not include an active region.
25. The semiconductor laser of claim 1 , wherein the curvature of the reflective surface is toroidal.