Single mode vertical cavity surface emitting laser using photonic crystals with a central defect

• US 6,810,056 B1
• Filed: 09/26/2002
• Issued: 10/26/2004
• Est. Priority Date: 09/26/2002
• Status: Expired due to Term

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Finisar Corporation (II-VI Incorporated)
• Inventors: Deng, Hongyu, Lipson, Jan, Lenosky, Thomas
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): VY, HUNG T
• Application Number:
  US10/256,001
• Time in Patent Office: 761 Days
• Field of Search: 372/43-46, 372/96-97, 372/50, 257/98
• US Class Current: 372/46.01
• CPC Class Codes: H01S 2301/166 Single transverse or lateral mode
• CPC Class Codes: H01S 5/11 Comprising a photonic bandgap structure
• CPC Class Codes: H01S 5/18319 comprising a periodical structure in lateral directions
• CPC Class Codes: H01S 5/18327 Structure being part of a DBR H01S5/18391 takes precedence

Abstract

A vertical cavity surface emitting laser (VCSEL) using photonic crystals with a central defect. At least one of the mirror layers of a VCSEL includes a photonic crystal with a central defect. The central defect, which is surrounded by a periodic structure of holes or cavities, permits laser light to propagate and exit the VCSEL. Semi-insulating regions are formed in the active region such that when cavities are drilled in the photonic crystal and penetrate the active region, the cavities pass through the semi-insulating regions. This reduces the surface recombination that would otherwise occur in the active region and prevents the threshold current from increasing. The photonic crystal with a central defect has a reflectivity that is wavelength dependent. The VCSEL thus emits a single mode.

Claims

1. A vertical cavity surface emitting laser comprising:

a lower mirror layer formed on a substrate, wherein the lower mirror layer includes a first plurality of distributed Bragg reflector layers;

an active region formed on the lower mirror layer, wherein the active region includes a plurality of quantum wells; and

an upper mirror layer formed on the active region, the upper mirror comprising;

a second plurality of distributed Bragg reflector layers having a first reflectivity;

a photonic crystal formed on the second plurality of distributed Bragg reflector layers; and

a plurality of holes formed in the photonic crystal in a periodic pattern to give the photonic crystal a second reflectivity for a particular mode, the combination of the first reflectivity and the second reflectivity causing the particular mode to lase.

2. A vertical cavity surface emitting laser as defined in claim 1, wherein plurality of holes is periodic except for the central defect, which does not contain any holes.

3. A vertical cavity surface emitting laser as defined in claim 2, wherein the lower mirror layer further comprises a photonic crystal that has a plurality of holes formed therein.

4. A vertical cavity surface emitting laser as defined in claim 1, wherein the plurality of holes in the photonic crystal are filled with air.

5. A vertical cavity surface emitting laser as defined in claim 1, wherein the upper mirror layer further comprises an extra photonic crystal that has a plurality of holes formed therein.

6. A vertical cavity surface emitting laser as defined in claim 1, wherein semi-insulating regions are formed in the active region.

7. A vertical cavity surface emitting laser as defined in claim 6, wherein the plurality of holes of the photonic crystal are extended through the semi-insulating regions to form semi-insulating rings in the active region.

8. A vertical cavity surface emitting laser as defined in claim 1, wherein the central defect includes at least one hole.

9. A vertical cavity surface emitting laser as defined in claim 8, wherein the at least one hole formed in the central defect has an ellipsoidal shape.

10. A vertical cavity surface emitting laser that emits a single mode, the vertical cavity surface emitting laser comprising:

a substrate;

a lower mirror layer formed on the substrate, wherein the lower mirror layer includes a plurality of distributed Bragg reflector layers;

an active region formed on the lower mirror layer, wherein the active region includes a plurality of quantum wells; and

an upper mirror layer formed on the active region, the upper mirror layer comprising;

a plurality of distributed Bragg reflector layers having a first reflectivity; and

a first photonic crystal having a plurality of holes formed therein around a central defect that does not include any holes, the photonic crystal having a second reflectivity for a single mode, the first reflectivity and the second reflectivity causing the single mode to lase while the second reflectivity inhibits other modes from lasing.

11. A vertical cavity surface emitting laser as defined in claim 10, wherein the lower mirror layer further comprises a lower photonic crystal that includes a plurality of holes formed therein.

12. A vertical cavity surface emitting laser as defined in claim 10, wherein the plurality of holes formed in the photonic crystal are filled with air.

13. A vertical cavity surface emitting laser as defined in claim 10, wherein the plurality of holes formed in the photonic crystal have a periodic structure.

14. A vertical cavity surface emitting laser as defined in claim 13, wherein the upper mirror layer further comprises a second photonic crystal formed on the first photonic crystal that has a periodic cavity structure.

15. A vertical cavity surface emitting laser as defined in claim 13, wherein semi-insulating regions are formed in the active region.

16. A vertical cavity surface emitting laser as defined in claim 15, wherein the plurality of holes formed in the first photonic crystal are formed to extend through the semi-insulating regions to form semi-insulating rings in the active region.

17. A vertical cavity surface emitting laser as defined in claim 10, wherein a lattice structure of the plurality of holes affects a wavelength of the single mode.

18. A vertical cavity surface emitting laser as defined in claim 10, wherein the single mode has a wavelength of at least 1.3 microns.

19. A vertical cavity surface emitting laser as defined in claim 10, wherein the central defect includes at least one hole, wherein the at least one hole has a shape that selects a particular polarization state.

20. A vertical cavity surface emitting laser as defined in claim 19, wherein the shape of the one hole is ellipsoidal.

21. A vertical cavity surface emitting laser that emits a single mode, the vertical cavity surface emitting laser comprising:

a substrate;

a lower mirror layer formed on the substrate, wherein the lower mirror layer includes a plurality of distributed Bragg reflector layers;

an active region formed on the lower mirror layer, wherein the active region includes a plurality of quantum wells;

a plurality of semi-insulating regions formed within the active region, wherein the semi-insulating regions are formed in a lattice structure; and

an upper mirror layer formed on the active region such that the active region and the semi-insulating regions are between the lower mirror layer and the upper mirror layer;

a photonic crystal formed on the upper mirror layer; and

a plurality of cavities formed such that each cavity extends from the photonic crystal through a semi-insulating region such that each semi-insulating region becomes a semi-insulating ring in the active region, wherein each semi-insulating ring reduces surface recombination of carriers at surfaces within each semi-insulating ring.

22. A vertical cavity surface emitting laser as defined in claim 21, wherein the lower mirror layer further comprises a photonic crystal with a plurality of cavities formed therein without a central defect.

23. A vertical cavity surface emitting laser as defined in claim 21, wherein each cavity formed in the upper photonic crystal has a depth that extends into the lower mirror layer through the semi-insulating regions.

24. A vertical cavity surface emitting laser as defined in claim 21, wherein the single mode has a wavelength that is equal or greater than 1.3 microns.

25. A vertical cavity surface emitting laser as defined in claim 21, wherein the central defect surrounds a cavity such that the central defect has a ring shape.

26. A vertical cavity surface emitting laser as defined in claim 25, wherein the cavity surrounded by the central defect has an ellipsoidal shape to select a polarization state for the emitted single mode.