Coupling system to a microsphere cavity

• US 6,389,197 B1
• Filed: 02/10/2000
• Issued: 05/14/2002
• Est. Priority Date: 02/10/1999
• Status: Expired due to Term

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Maleki, Lute, Yao, Steve, Wu, Chi, Iltchenko, Vladimir
• Primary Examiner(s): Palmer, Phan T. H.
• Application Number:
  US09/501,824
• Time in Patent Office: 824 Days
• Field of Search: 385/14, 385/9, 385/27-39, 385/42-50
• US Class Current: 385/28
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• CPC Class Codes: G02B 6/10 of the optical waveguide type G02B6/02, G02B6/24 take precedence; devices or arrangements for the control of light by electric, magnetic, electro-magnetic or acoustic means G02F1/00; transferring the modulation of modulated light G02F2/00; optical logic elements G02F3/00; optical analogue/digital converters G02F7/00
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/262 Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements
• CPC Class Codes: G02B 6/264 with optical elements between opposed fibre ends which perform a function other than beam splitting having lens focusing means G02B6/32; utilising prism or grating G02B6/34
• 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 3/083 Ring lasers fibre ring lasers H01S3/06791
• CPC Class Codes: H01S 5/1032 Coupling to elements comprising an optical axis that is not aligned with the optical axis of the active region
• CPC Class Codes: H01S 5/1075 Disk lasers with special modes, e.g. whispering gallery lasers

Abstract

A system of coupling optical energy in a waveguide mode, into a resonator that operates in a whispering gallery mode. A first part of the operation uses a fiber in its waveguide mode to couple information into a resonator e.g. a microsphere. The fiber is cleaved at an angle Φ which causes total internal reflection within the fiber. The energy in the fiber then forms an evanescent field and a microsphere is placed in the area of the evanescent field. If the microsphere resonance is resonant with energy in the fiber, then the information in the fiber is effectively transferred to the microsphere.

Claims

1. A method of coupling between a waveguide mode and a whispering gallery mode, comprising:

forming a portion of a waveguide element, which operates in a waveguide mode, said portion having a part that induces total internal reflection which causes an evanescent field to be formed in an area of said waveguide and such that radiation in said waveguide mode forms said evanescent field at said area; and

placing a resonator, which operates in a whispering gallery mode, in said area of said evanescent field.

2. A method as in claim 1 further comprising placing another waveguide adjacent said resonator, to couple said radiation between said wave guide element and said another waveguide.

3. A method as in claim 2 wherein each of said waveguides and said resonator are fabricated on a surface of a chip.

4. A method as in claim 3 further comprising holding the resonator in a way such that a specified portion of the resonator is at a specified location relative to said waveguide.

5. A method as in claim 4 wherein said resonator is a microsphere in said specified location.

6. A method as in claim 3 wherein said chip comprises a first waveguide portion on a first chip, a second waveguide portion on a second chip, and a resonator holding portion disposed between said first and second chips.

7. A method as in claim 3 wherein both said first and second waveguides are on the same chip.

8. A method as in claim 2 further comprising using said resonator in said area of said evanescent field as a filter.

9. A method as in claim 2 wherein said part that induces total internal reflection includes a corner reflector.

10. A method as in claim 2 wherein said part that induces total internal reflection which includes an angled end portion of the waveguide.

11. A method as in claim 2 wherein said part that induces total internal reflection includes a mirror.

12. A method as in claim 1 wherein said resonator is a microsphere resonator.

13. A method as in claim 12 further comprising matching a position of the microsphere resonator to an area of the evanescent field.

14. A method as in claim 1, wherein said resonator is a resonator which is resonant in said whispering gallery mode.

15. A method of coupling between a waveguide mode and a whispering gallery mode, comprising:

forming a portion of a waveguide element which is a single mode fiber, which operates in a waveguide mode, said portion which causes an evanescent field to be formed in an area of said waveguide and such that radiation in said waveguide mode forms said evanescent field at said area; and

placing a resonator, which operates in a whispering gallery mode, in said area of said evanescent field.

16. A method as in claim 15 wherein said single mode fiber has an end which cleaved to a specified angle which causes total internal reflection to form said evanescent field.

17. A method as in claim 16 wherein said specified angle secures a phase matching requirement.

18. A method as in claim 17 wherein said phase matching requirement forms an angle Φ

=arc sin n_sphere/n_fiber where n_fiber is a refractive refraction index that describes guided wave and fiber trunk core truncation area, and n_sphere is an effective refraction index of the azimuthal propagation of the waveguide modes.

19. A method as in claim 15 further comprising another fiber near said resonator to enable coupling from said fiber to said another fiber.

20. A method of coupling information to a resonator, comprising:

forming a surface grating on the resonator; and

phase matching optical energy to said surface grating to induce said optical energy to enter said resonator.

21. A method as in claim 20 further comprising forming said grating by obtaining a resonator, forming a photosensitive layer on said resonator, and using a light source to form a grating on an outside of said resonator.

22. A method as in claim 21 wherein said forming a photosensitive layer comprises melting germanium oxide doped glass powder and forming said powder on the outside of the resonator.

23. A method as in claim 22 wherein said forming a grating comprises using a ultraviolet light from a laser to form said grating.

24. A method as in claim 20 further comprising a collimating lens, coupling said optical energy towards said grating.

25. A method of coupling light from an optical fiber into a whispering gallery type resonator, comprising:

transmitting light through a core of the optical fiber;

forming a cleave on the optical fiber at a specified angle which causes total internal reflection and which forms an evanescent field outside the fiber; and

locating said resonator in the location of said evanescent field to come into contact with the evanescent field.

26. A method of coupling energy, comprising:

coupling light in a waveguide mode to an ending part that causes said light to produce an evanescent field; and

locating a device which has a resonant whispering gallery mode, in the location of said evanescent field to come in contact with the evanescent field and to induce energy in said whispering gallery node based on said evanescent field.