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

• US 7,768,024 B2
• Filed: 12/04/2006
• Issued: 08/03/2010
• Est. Priority Date: 12/02/2005
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Nakamura, Shuji, Weisbuch, Claude C. A.
• Primary Examiner(s): Pham; Long
• Application Number:
  US11/633,148
• Publication Number:
  US 20070125995A1
• Time in Patent Office: 1,338 Days
• Field of Search: 257/98, 257/79, 257/13, 257/29, 257/31, 257/32
• US Class Current: 257/98
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: H01L 21/02647 Lateral overgrowth
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01S 2304/12 Pendeo epitaxial lateral overgrowth [ELOG], e.g. for growing GaN based blue laser diodes
• CPC Class Codes: H01S 5/11 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 5/1206 having a non constant or multiplicity of periods
• CPC Class Codes: H01S 5/1215 Multiplicity of periods
• CPC Class Codes: H01S 5/1225 with a varying coupling constant along the optical axis
• CPC Class Codes: H01S 5/1231 Grating growth or overgrowth details
• CPC Class Codes: H01S 5/18 Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
• CPC Class Codes: H01S 5/187 using Bragg reflection
• CPC Class Codes: H01S 5/20 Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
• CPC Class Codes: H01S 5/2004 Confining in the direction perpendicular to the layer structure
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

A structure using integrated optical elements is comprised of a substrate, a buffer layer grown on the substrate, one or more first patterned layers deposited on top of the buffer layer, wherein each of the first patterned layers is comprised of a bottom lateral epitaxial overgrowth (LEO) mask layer and a LEO nitride layer filling holes in the bottom LEO mask layer, one or more active layers formed on the first patterned layers, and one or more second patterned layers deposited on top of the active layer, wherein each of the second patterned layers is comprised of a top LEO mask layer and a LEO nitride layer filling holes in the top LEO mask layer, wherein the top and/or bottom LEO mask layers act as a mirror, optical confinement layer, grating, wavelength selective element, beam shaping element or beam directing element for the active layers.

Claims

1. A structure using integrated optical elements, comprising:

(a) a substrate;

(b) a buffer layer grown on the substrate;

(c) one or more first patterned layers deposited on top of the buffer layer, wherein each of the first patterned layers is comprised of a bottom lateral epitaxial overgrowth (LEO) mask layer and a first LEO nitride layer filling holes in the bottom LEO mask layer;

(d) one or more active layers formed on the first patterned layers; and

(e) one or more second patterned layers deposited on top of the active layer, wherein each of the second patterned layers is comprised of a top LEO mask layer and a second LEO nitride layer filling holes in the top LEO mask layer;

(f) wherein the top, bottom, or top and bottom LEO mask layers, act as a mirror, optical confinement layer, grating, wavelength selective element, beam shaping element or beam directing element for the active layers.

2. The structure of claim 1, wherein the first, second, or first and second patterned layers, due to a refractive index difference with the active layers, efficiently confine a laser mode to the active layers.

3. The structure of claim 1, wherein the first, second, or first and second patterned layers provide a current aperture giving a gain guided action.

4. The structure of claim 1, wherein the first, second, or first and second patterned layers provide lateral waveguiding for a laser mode in the active layers.

5. The structure of claim 1, wherein the first, second, or first and second patterned layers isolate a laser mode from one or more electrodes on the structure, thus diminishing absorption losses.

6. The structure of claim 1, wherein the top and bottom LEO mask layers comprise silicon dioxide.

7. The structure of claim 1, wherein one of the first or second patterned layers does not diffract.

8. The structure of claim 7, wherein the one of the first or second patterned layers that does not diffract is patterned as an ensemble of stripes along a direction of laser light propagation.

9. The structure of claim 8, wherein the one of the first or second patterned layers that does not diffract comprises end regions that are patterned with diffracting or reflecting elements.

10. The structure of claim 1, wherein the first or second patterned layers comprise a separate gain and two mirror regions.

11. The structure of claim 10, wherein patterns of the gain and mirror regions have different periods.

12. The structure of claim 10, wherein at least one of the mirror regions is an extraction region for extracting or outcoupling.

13. The structure of claim 12, wherein the separate gain, mirror and extraction regions have different growth depths, defined by etching of the first or second patterned layers, to provide improved mirror properties for lasing in the separate gain and mirror regions and outcoupling in the extraction region, and wherein a guided mode interacts more strongly with patterned columns in the mirror regions.

14. The structure of claim 1, wherein the second patterned layer is doped with either an n-type impurity or a p-type impurity.

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

(a) growing a buffer layer on a substrate;

(b) depositing one or more first patterned layers on top of the buffer layer, wherein each of the first patterned layers is comprised of a bottom lateral epitaxial overgrowth (LEO) mask layer and a first LEO nitride layer filling holes in the bottom LEO mask layer;

(c) forming one or more active layers on the first patterned layers; and

(d) depositing one or more second patterned layers on top of the active layers, wherein each of the second patterned layers is comprised of a top LEO mask layer and a second LEO nitride layer filling holes in the top LEO mask layer;

(e) 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.

16. A structure using integrated optical elements, comprising:

(a) a substrate;

(b) a buffer layer on the substrate, one or more bottom confining layers on the buffer layers and one or more active layers grown on the bottom confining layers; and

(c) one or more patterned layers deposited on top of the active layers, wherein each of the patterned layers is comprised of a top LEO mask layer and a LEO nitride layer filling holes in the top LEO mask layer;

(d) wherein the top LEO mask layers act as a mirror, optical confinement layer, grating, wavelength selective element, beam shaping element or beam directing element for the active layers.

17. The structure of claim 16, wherein the patterned layers, due to a refractive index difference with the active layers, efficiently confine a laser mode to the active layer.

18. The structure of claim 16, wherein the patterned layers provide a current aperture giving gain guided action.

19. The structure of claim 16, wherein the patterned layers provide lateral waveguiding for a laser mode in the active layers.

20. The structure of claim 16, wherein the patterned layers isolate a laser mode from one or more electrodes, thus diminishing absorption losses.

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

(a) growing a buffer layer on a substrate, growing one or more bottom confining layers on the buffer layer, and growing one or more active layers on the bottom confining layers;

(b) depositing one or more patterned layers on top of the active layers, wherein each of the patterned layers is comprised of a top LEO mask layer and a LEO nitride layer filling holes in the top LEO mask layer;

(c) wherein the patterned layers act as a mirror, optical confinement layer, grating, wavelength selective element, beam shaping element or beam directing element for the active layers.