Horizontal emitting, vertical emitting, beam shaped, distributed feedback (DFB) lasers by growth over a patterned substrate

• US 7,723,745 B2
• Filed: 02/13/2008
• Issued: 05/25/2010
• Est. Priority Date: 02/28/2005
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Speck, James S., DenBaars, Steven P., David, Aurelien J. F., Weisbuch, Claude C. A.
• Primary Examiner(s): Picardat; Kevin M
• Application Number:
  US12/030,697
• Publication Number:
  US 20080128737A1
• Time in Patent Office: 832 Days
• Field of Search: 438/29, 438/31, 438/32, 438/36, 438/37, 438/69, 438/71, 438/72, 257/13, 257/79, 257/81, 257/98
• US Class Current: 257/98
• CPC Class Codes: H01S 2304/12 Pendeo epitaxial lateral overgrowth [ELOG], e.g. for growing GaN based blue laser diodes
• CPC Class Codes: H01S 5/1021 Coupled cavities H01S5/14 takes precedence
• CPC Class Codes: H01S 5/11 Comprising a photonic bandgap structure
• CPC Class Codes: H01S 5/12 the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers comprising a photonic bandgap structure H01S5/11; surface-emitting lasers H01S5/18
• CPC Class Codes: H01S 5/187 using Bragg reflection
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP

Abstract

A structure using integrated optical elements is comprised of a substrate, a buffer layer grown on the substrate, one or more patterned layers formed on the buffer layer and one or more active layers formed on or between the patterned layers, for instance by Lateral Epitaxial Overgrowth (LEO), and including one or more light emitting species. The patterned layer comprises a mask (made of insulating, semiconducting or metallic material) and material filling holes in the mask. The patterned layer, due to a large index difference with the active layer and/or variations of a refractive index between the mask and materials filling holes in the mask, acts as an optical confinement layer, a mirror, a diffraction grating, a wavelength selective element, a beam shaping element or a beam directing element.

Claims

1. A structure using integrated optical elements, comprising:

(a) a substrate;

(b) one or more patterned layers deposited on the substrate, wherein the patterned layers comprise a patterned mask perforated or pierced by an array of holes; and

(c) one or more active layers formed on or between the patterned layers, wherein the patterned mask acts as a growth mask for the active layers;

(d) wherein the patterned layers and active layers are nitride-based layers.

2. The structure of claim 1, wherein the active layers include one or more light emitting species.

3. The structure of claim 1, wherein each patterned layer acts as a mirror, optical confinement layer, grating, wavelength selective element, beam shaping element or beam directing element for the active layers.

4. The structure of claim 1, wherein the patterned layer has a large average index difference with the active layer.

5. The structure of claim 1, wherein at least a portion of the patterned layer acts as a diffraction grating and the structure emits guided light outside a device plane by having guided light shaped into extracted light using the diffraction grating.

6. The structure of claim 1, wherein at least a portion of the patterned layer acts as a distributed feedback (DFB) grating for single wavelength emission of light from the structure.

7. The structure of claim 1, wherein the patterned layer defines a plurality of coupled cavities.

8. The structure of claim 1, wherein the patterned layer, due to a large index difference with the active layer, modifies an emission pattern of light emitting species in the active layer, in order to increase or decrease a relative amount of light emitted in guided, radiative or leaky modes.

9. The structure of claim 1, wherein the patterned layer includes a master oscillator (MO) back mirror and coupling mirror, power amplifier (PA) active region, and anti-eflection (AR) outcoupler, and the anti-reflection outcoupler comprises an initial region, anti-reflection region that performs mode conversion with reflection, and vertical extractor that is a final outcoupler.

10. The structure of claim 1, wherein the patterned layer comprises confining regions having designed growth such that absorption is diminished or suppressed in regions adjacent to an amplifying region.

11. The structure of claim 1, wherein the substrate is sapphire.

12. The structure of claim 1, wherein each of the patterned layers is comprised of a mask and materials filling holes in the mask.

13. The structure of claim 12, wherein the mask is comprised of an insulating, semiconducting or metallic material.

14. The structure of claim 12, wherein the patterned layer has variations in a refractive index between the mask and materials filling holes in the mask.

15. The structure of claim 12, wherein the materials filling holes in the mask are nitride materials.

16. The structure of claim 12, wherein one or more properties of the patterned layer are spatially varied across the structure, and the properties of the patterned layer comprise thickness, radius of the holes in the mask, shape of the holes in the mask, periodicity of a pattern in the mask, or non-periodicity of a pattern in the mask.

17. A method of fabricating a structure using integrated optical elements, comprising:

(a) depositing one or more patterned layers on a substrate, wherein the patterned layers comprise a patterned mask perforated or pierced by an array of holes; and

(b) forming one or more active layers on or between the patterned layers, wherein the patterned mask acts as a growth mask for the active layers;

(c) wherein the patterned layers and active layers are nitride-based layers.

18. The method of claim 17, wherein the active layers include one or more light emitting species.

19. The method of claim 17, wherein each patterned layer acts as a mirror, optical confinement layer, grating, wavelength selective element, beam shaping element or beam directing element for the active layers.

20. The method of claim 17, wherein the patterned layer has a large average index difference with the active layer.

21. The method of claim 17, wherein at least a portion of the patterned layer acts as a diffraction grating and the structure emits guided light outside a device plane by having guided light shaped into extracted light using the diffraction grating.

22. The method of claim 17, wherein at least a portion of the patterned layer acts as a distributed feedback (DFB) grating for single wavelength emission of light from the structure.

23. The method of claim 17, wherein the patterned layer defines a plurality of coupled cavities.

24. The method of claim 17, wherein the patterned layer, due to a large index difference with the active layer, modifies an emission pattern of light emitting species in the active layer, in order to increase or decrease a relative amount of light emitted in guided, radiative or leaky modes.

25. The method of claim 17, wherein the patterned layer includes a master oscillator (MO) back mirror and coupling mirror, power amplifier (PA) active region, and anti-reflection (AR) outcoupler, and the anti-reflection outcoupler comprises an initial region, anti-reflection region that performs mode conversion with reflection, and vertical extractor that is a final outcoupler.

26. The method of claim 17, wherein the patterned layer comprises confining regions having designed growth such that absorption is diminished or suppressed in regions adjacent to an amplifying region.

27. The method of claim 17, wherein the substrate is sapphire.

28. The method of claim 17, wherein each of the patterned layers is comprised of a mask and materials filling holes in the mask.

29. The method of claim 28, wherein the mask is comprised of an insulating, semiconducting or metallic material.

30. The method of claim 28, wherein the patterned layer has variations in a refractive index between the mask and materials filling holes in the mask.

31. The method of claim 28, wherein the materials filling holes in the mask are nitride materials.

32. The method of claim 28, wherein one or more properties of the patterned layer are spatially varied across the structure, and the properties of the patterned layer comprise thickness, radius of the holes in the mask, shape of the holes in the mask, periodicity of a pattern in the mask, or non-periodicity of a pattern in the mask.

33. A structure fabricated using the method of claim 17.