Narrow lateral waveguide laser
As edge-emitting semiconductor laser incorporating a narrow waveguide design is disclosed. The narrow waveguide expands the lateral mode size, creates a large modal spot size, and insures higher-order modes are beyond cutoff. Separate current confinement allows the current injection region to match the mode size. The resulting device exhibits single-mode operation with a large spot-size to high output powers.
1. A semiconductor laser comprising:
at least one quantum well;
one or more transverse waveguide layers surrounding the at least one quantum well;
a first cladding layer located below the transverse waveguide layers;
a lateral guide structure located proximate the transverse waveguide layers, the lateral guide structure having a first index and configured to create a narrow-waveguide mode;
blocking structures located proximate the lateral guide structure and providing lateral confinement of current to a region surrounding the lateral guide structure; and
a second cladding layer located above the lateral guide structure, the second cladding layer having a second index, wherein the first index is higher than the second index.
2. The semiconductor laser of claim 1 wherein the lateral guide structure has a thickness of 50 to 300 nm.
3. The semiconductor laser of claim 1 wherein the lateral guide structure has a width of 3.0 μm or less.
4. The semiconductor laser of claim 1 wherein the blocking structures are located on a common lateral plane as the lateral guide structure.
5. The semiconductor laser of claim 1 wherein the lateral guide structure is doped with a p-type dopant.
6. The semiconductor laser of claim 1 wherein the lateral guide structure has a cross-sectional thickness of less than 250 nm.
7. The semiconductor laser of claim 1 wherein the lateral guide structure includes GaAs.
8. The semiconductor laser of claim 1 , wherein blocking structures are made of InGaP, InGaAsP, AlGaAs, GaAs or some combination of these materials.
9. The semiconductor laser of claim 1 , wherein blocking structures are formed by means of an implant such as Si, P, Ge, C, or some combination of these materials such that a reverse-biased P-N junction is created.
10. The semiconductor laser of claim 1 wherein blocking structures are formed by means of an implant such as H or Si such that a semi-insulating layer is created.
11. A method of forming a semiconductor laser device, the method comprising:
forming an active layer, one or more transverse waveguide layers, and a first cladding layer above a substrate;
forming a guide layer proximate the active layer;
patterning the guide layer to form a narrow waveguide;
forming blocking structures that provide lateral current confinement to a region surrounding the patterned guide; and
forming a second cladding layer above the patterned guide and blocking structures.
12. The method of claim 11 wherein the patterned guide comprises a lateral waveguide including GaAs.
13. The method of claim 11 wherein the patterned guide comprises InGaAsP or AlGaAs.
14. The method of claim 11 wherein the active layer comprises a plurality of quantum wells.
15. The method of claim 11 wherein the blocking structures comprise n-doped InGaP.
16. The method of claim 11 wherein the blocking structures comprise a reverse-biased PN junction formed by implant.
17. The method of claim 11 wherein the blocking structures comprise a semi-insulating region formed by implant.
18. The method of claim 11 wherein the patterned guide has a width of approximately 3.0 μm or less.
19. An edge-emitting semiconductor laser including a narrow waveguide design, the laser comprising:
a transverse waveguide core including one or more quantum wells;
a lateral waveguide located proximate the transverse waveguide core and being configured to create a narrow-waveguide mode; and
blocking structures located proximate the lateral waveguide and configured to confine the current to a region surrounding the lateral waveguide.
20. The laser of claim 19 wherein the lateral waveguide has a width approximately 3.0 μm or less.
21. The laser of claim 19 wherein the quantum wells comprise InGaAs.
22. The laser of claim 19 wherein the transverse waveguide core comprises a barrier layer.
23. The laser of claim 22 wherein the barrier layers comprise InGaAsP.
24. The laser of claim 19 wherein the blocking structures comprise alternating PN junction layers.
25. The laser of claim 19 wherein the blocking structures comprise semi-insulating layers.