Vertical-cavity surface-emitting lasers with non-periodic gratings

1. A surface-emitting laser comprising:

a grating layer configured with a non-periodic, sub-wavelength grating, the grating comprising a pattern of sub-wavelength grating features being spaced apart from each other and having a defined refractive index that is approximately equal with respect to each other, the pattern of sub-wavelength grating features comprising a plurality of sub-regions of the sub-wavelength grating features, the sub-wavelength grating features within each sub-region having dimensions corresponding to a selected period and duty cycle that is distinct with respect to the other respective sub-regions of the plurality of sub-regions;

a reflective layer; and

a light-emitting layer disposed between the grating layer and the reflective layer, wherein the sub-wavelength grating and the reflective layer form a resonant cavity, and the grating is configured via the pattern of sub-wave-length grating features to shape one or more internal cavity modes and to shape one or more external transverse modes of light emitted from the surface-emitting laser,

wherein the pattern of sub-wavelength grating features is a one-dimensional pattern of lines separated by grooves in each of the plurality of sub-regions.

2. The surface-emitting laser of claim 1 further comprises:

a substrate disposed on the reflective layer;

a first electrode disposed on the substrate; and

a second electrode disposed on the grating layer, the second electrode configured with an opening exposing the sub-wavelength grating.

3. The surface-emitting laser of claim 1 wherein the reflective layer further comprises a distributed Bragg reflector.

4. The surface-emitting laser of claim 1 wherein the reflective layer further comprises a second grating layer configured with a second non-periodic, sub-wavelength grating.

5. The surface-emitting laser of claim 1 wherein the sub-wavelength grating further comprises a suspended membrane that forms an air gap between the sub-wavelength grating and the light-emitting layer.

6. The surface-emitting laser of claim 1 further comprising an insulating layer disposed between the light-emitting layer and the grating layer, the insulting layer includes an opening for current and optical confinement.

7. The surface-emitting laser of claim 1 wherein the light amplified within, and emitted from, the resonant cavity is polarized based on the grating pattern of the sub-wavelength grating.

8. The surface-emitting laser of claim 1 wherein the sub-wavelength grating and the reflective layer are configured to form a single mode resonant cavity for emitting a single mode of light.

9. The surface-emitting laser of claim 1 , wherein each sub-wavelength feature of the pattern of sub-wavelength grating features is spaced apart from each other by air.

10. A method for generating light, the method comprising:

electronically pumping a light-emitting layer to emit light formed within a resonant cavity including one or more non-periodic, sub-wavelength gratings, each of the one or more non-periodic, sub-wavelength gratings comprising a pattern of sub-wavelength grating features that comprises a plurality of sub-regions of the sub-wavelength grating features, the sub-wavelength grating features within each sub-region having dimensions corresponding to a selected period and duty cycle that is distinct with respect to the other respective sub-regions of the plurality of sub-regions;

coupling light into axial and transverse modes supported by the cavity;

amplifying light coupled into the lowest loss axial and transverse modes supported by the cavity, based on the configuration of the one or more grating layers, to shape a wavefront of the light from a substantially planar wavefront to a substantially curved wavefront; and

emitting a coherent beam of light comprising the substantially curved wave-front matching the axial and transverse modes supported by the cavity.

11. The method of claim 10 emitting a mode of coherent beam of light further comprises emitting a single mode of light supported by the cavity.

12. The method of claim 10 further comprising amplifying modes of light with a particular polarization supported by the cavity.

13. The method of claim 12 further comprising the one or more gratings configured to reflect light with a particular polarization.

14. The method of claim 10 wherein the pattern of sub-wavelength grating features is a one-dimensional pattern of lines separated by grooves in each of the plurality of sub-regions.

15. The method of claim 10 , wherein the pattern of sub-wavelength grating features are spaced apart from each other and have a defined refractive index that is approximately equal with respect to each other.

16. The method of claim 10 , wherein the pattern of sub-wavelength grating features are arranged to enable the grating to operate as a cylindrical mirror or a spherical mirror to provide the substantially curved wavefront.

17. A surface-emitting laser comprising:

a grating layer configured with a non-periodic, sub-wavelength grating, the grating comprising a pattern of sub-wavelength grating features being spaced apart from each other and having a defined refractive index that is approximately equal with respect to each other, the pattern of sub-wavelength grating features comprising a plurality of sub-regions of the sub-wavelength grating features, the sub-wavelength grating features within each sub-region having dimensions corresponding to a selected period and duty cycle that is distinct with respect to the other respective sub-regions of the plurality of sub-regions;

a reflective layer; and

a light-emitting layer disposed between the grating layer and the reflective layer, wherein the sub-wavelength grating and the reflective layer form a resonant cavity, and the grating is configured via the pattern of sub-wavelength grating features to shape one or more internal cavity modes and to shape one or more external transverse modes of light emitted from the surface-emitting laser,

wherein the pattern of sub-wavelength grating features is configured to shape the one or more internal cavity modes and to shape the one or more external transverse modes to shape a wavefront of the light emitted from the surface-emitting laser from a substantially planar wavefront to a substantially curved wavefront.

18. The surface-emitting laser of claim 17 wherein the reflective layer further comprises a second grating layer configured with a second non-periodic, sub-wavelength grating.

19. The surface-emitting laser of claim 17 wherein the pattern of sub-wavelength grating features comprises a two-dimensional pattern of sub-wave-length grating features.

20. The surface-emitting laser of claim 17 wherein the sub-wavelength grating further comprises a suspended membrane that forms an air gap between the sub-wavelength grating and the light-emitting layer.