Surface functionalization of micro-resonators

• US 20050163185A1
• Filed: 12/17/2004
• Published: 07/28/2005
• Est. Priority Date: 10/02/2002
• Status: Abandoned Application

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Vahala, Kerry J., Yang, Lan, Armani, Deniz K.
• Application Number:
  US11/016,067
• Publication Number:
  US 20050163185A1
• Time in Patent Office: Days
• US Class Current: 372/67
• CPC Class Codes: G02B 6/29341 Loop resonators operating in a whispering gallery mode evanescently coupled to a light guide, e.g. sphere or disk or cylinder evanescent coupling for sensing fluorescence G01N21/648
• CPC Class Codes: H01S 3/0604 in the form of a plate or disc
• CPC Class Codes: H01S 3/0612 Non-homogeneous structure H01S3/07 takes precedence
• CPC Class Codes: H01S 3/0627 the resonator being monolithic, e.g. microlaser
• CPC Class Codes: H01S 3/083 Ring lasers fibre ring lasers H01S3/06791
• CPC Class Codes: H01S 3/1608 erbium

Abstract

A micro-cavity resonator including a micro-cavity having a doped sol gel layer or solution applied thereto. The dopant can be various rare earth elements, such as erbium. The micro-cavity can be a spherical or disk or toroid shaped micro-cavity. Certain cavities are capable of high and ultra-high Q factors. Optical energy travels along an inner surface of the coated micro-cavity at a wavelength influenced or determined by the dopant in the coating.

Claims

1. A micro-cavity resonator, comprising:

an optical micro-cavity;

a dopant; and

a sol gel solution, wherein the sol gel solution hosts the dopant, and at least a portion of the micro-cavity is coated with the doped sol gel solution, and whereby optical energy travels along an inner surface of the coated micro-cavity at a wavelength that is influenced by the dopant in the sol gel coating.

2. The resonator of claim 1, the dopant comprising a rare earth element.

3. The resonator of claim 2, the rare earth element comprising erbium.

4. The resonator of claim 3, the concentration of erbium in the sol gel solution being about 10¹⁸ to 10²² cm³.

5. The resonator of claim 3, wherein the erbium doped sol gel solution coated micro-cavity emits an output at a wavelength of about 1.5 to 1.6 micrometers.

6. The resonator of claim 1, a thickness of the sol gel coating being at least about 0.5 micrometer.

7. The resonator of claim 1, the micro-cavity having a Q factor of about 10⁶ to 10⁷.

8. The resonator of claim 1, the micro-cavity comprising a planar micro-cavity.

9. The resonator of claim 1, the micro-cavity comprising silica.

10. The resonator of claim 1, the micro-cavity comprising a spherical micro-cavity.

11. The resonator of claim 1, the micro-cavity comprising a toroid-shaped micro-cavity.

12. The resonator of claim 1, the entire micro-cavity surface being coated with the doped sol gel solution.

13. The resonator of claim 1, a resonant mode within the coated micro-cavity comprising a whispering-gallery mode.

14. A micro-cavity resonator, comprising:

a spherical optical micro-cavity;

a sol gel solution; and

a dopant,

wherein the sol gel solution hosts the dopant, and at least a portion of the spherical micro-cavity is coated with the doped sol gel solution, whereby the doped sol gel coating functionalizes a gain of the spherical micro-cavity, and optical energy travels along an inner surface of the coated micro-cavity at a wavelength influenced by the doped sol gel coating.

15. The resonator of claim 14, the dopant comprising erbium.

16. The resonator of claim 15, the concentration of erbium in the doped sol gel solution being about 10¹⁸ to 10²² cm⁻

3.

17. The resonator of claim 16, wherein the coated spherical micro-cavity emits an output at a wavelength of about 1.5 to about 1.6 micrometers.

18. The resonator of claim 14, a thickness of the doped sol gel coating being at least about 0.5 half micrometer.

19. The resonator of claim 14, the spherical micro-cavity having a Q factor of about 10⁶ to 10⁷.

20. The resonator of claim 14, the spherical micro-cavity comprising silica.

21. The resonator of claim 14, the spherical micro-cavity having a diameter of about 25 to 200 μ

m, wherein a thickness of the doped sol gel coating is at least about half micrometer.

22. The resonator of claim 14, the entire spherical micro-cavity surface being coated with the doped sol gel solution.

23. The resonator of claim 14, a resonant mode within the coated spherical micro-cavity comprising a whispering-gallery mode.

24. A micro-cavity resonator, comprising:

a micro-cavity;

a substrate, wherein portions of the substrate located below the micro-cavity are removed to form a pillar, the pillar supporting the micro-cavity;

a sol gel solution; and

a dopant,

wherein the sol gel solution includes the dopant and at least a portion of the micro-cavity is coated with the doped sol gel solution, whereby optical energy travels along an inner surface of the coated micro-cavity and has a wavelength influenced by the dopant in the sol gel coating.

25. The resonator of claim 24, the dopant comprising erbium.

26. The resonator of claim 25, the concentration of erbium in the doped sol gel coating being about 10¹⁸ cm⁻

3 to 10²² cm<sup>−

3</sup>.

27. The resonator of claim 24, wherein the coated spherical micro-cavity emits an output at a 0 wavelength of about 1.5 to about 1.6 micrometers.

28. The resonator of claim 24, a thickness of the doped sol gel coating being at least about 0.5 micrometer.

29. The resonator of claim 24, the micro-cavity comprising a high Q micro-cavity.

30. The resonator of claim 24, the micro-cavity having a Q factor of about 10⁶ to 10⁸.

31. The resonator of claim 24, the micro-cavity comprising silica.

32. The resonator of claim 24, a majority of the micro-cavity surface having the doped sol gel coating.

33. The resonator of claim 24, the entire micro-cavity surface being coated with the doped sol gel solution.

34. The resonator of claim 24, the micro-cavity having a toroid shape.

35. The resonator of claim 34, the toroid-shaped micro-cavity having a thickness of about 0.5 to about ten micrometers.

36. The resonator of claim 24, the micro-cavity being substantially parallel to a top surface of the pillar.

37. The resonator of claim 24, wherein a periphery of the micro-cavity extends beyond a top of the pillar.

38. The resonator of claim 24, a resonant mode within the coated micro-cavity comprising a whispering-gallery mode.

39. The resonator of claim 24, the substrate comprising a silicon substrate.

40. The resonator of claim 24, the pillar having an isotropic surface.

41. The resonator of claim 24, the pillar having a tapered shape.

42. The resonator of claim 24, the micro-cavity comprising a disk, wherein a diameter of the disk becomes smaller when heated.

43. The resonator of claim 42, wherein the diameter of the disk decreases until the molten disk material collapses, after which the diameter remains substantially constant.

44. The resonator of claim 42, the heated disk sections forming a toroid micro-cavity.

45. The resonator of claim 24, the micro-cavity being substantially circular and having a diameter of about 25 micrometers to about 200 micrometers.

46. A method of functionalizing a surface of a micro-cavity, comprising:

providing the micro-cavity;

providing a sol gel solution;

providing a dopant;

introducing the dopant into the sol gel solution; and

coating at least a portion of the micro-cavity with the doped sol gel solution, whereby optical energy travels along an inner surface of the coated micro-cavity at a wavelength that is influenced by the dopant in the sol gel coating.

47. The method of claim 46, providing the micro-cavity further comprising providing a spherical micro-cavity.

48. The method of claim 46, providing the micro-cavity further comprising providing a toroid-shaped micro-cavity.

49. The method of claim 46, providing the micro-cavity further comprising providing a micro-cavity that is supported by a pillar.

50. The method of claim 49, providing the micro-cavity further comprising providing a micro-cavity that includes a periphery that extends beyond a top of the pillar.

51. The method of claim 46, wherein providing the doped sol gel solution further comprises providing an erbium doped sol gel solution.

52. The method of claim 51, wherein providing the erbium doped sol gel solution further comprises providing an erbium doped sol gel solution produced by the following steps:

hydrolyzing tetraethoxysilane (TEOS) in water under an acid condition with a co-solvent;

adding erbium ions to the hydrolyzed tetraethoxysilane;

stirring the mixture of the erbium ions and the hydrolyzed tetraethoxysilane; and

aging the stirred mixture, thereby forming an erbium doped silica sol gel solution.

53. The method of claim 52, wherein hydrolyzing further comprises hydrolyzing tetraethoxysilane (TEOS) in water under an acid condition with isopropanol as the co-solvent.

54. The method of claim 52, wherein adding erbium ions further comprises adding ErNO₃.5H₂O to the hydrolyzed TEOS solution

55. The method of claim 52, wherein stirring the mixture further comprises stirring the mixture at about 70°

C.

56. The method of claim 52, wherein aging the stirred mixture further comprises aging the stirred mixture at about ambient temperature for about three to ten hours.

57. The method of claim 52, wherein coating the micro-cavity surface further comprises immersing the micro-cavity in the doped sol gel solution.

58. The method of claim 46, wherein immersing further comprises

immersing the micro-cavity into the doped sol gel solution for about 20 minutes, and

heating the micro-cavity in an oven at about 160°

C. for 10 minutes.

59. The method of claim 46, wherein the immersing step results in application of a doped sol gel solution coating having a thickness of about 0.3 μ

m/cycle.

60. The method of claim 46, further comprising repeating the coating step until a desired doped sol gel solution coating thickness is achieved.

61. The method of claim 46, further comprising irradiating the coated micro-cavity with a laser.

62. The method of claim 61, further comprising inducing flow of the doped sol gel coating.

63. The method of claim 62, further comprising forming a toroid-shaped micro-cavity as a result of reflowing the doped sol gel coating.