Radiation-free optical cavity

• US 7,224,868 B2
• Filed: 10/24/2002
• Issued: 05/29/2007
• Est. Priority Date: 10/24/2001
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Joannopoulos, John D., Johnson, Steven G., Watts, Michael R., Haus, Hermann A.
• Primary Examiner(s): Wells; Nikita
• Assistant Examiner(s): Johnston; Phillip A.
• Application Number:
  US10/279,777
• Publication Number:
  US 20030118289A1
• Time in Patent Office: 1,678 Days
• Field of Search: 385/39
• US Class Current: 385/39
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 2006/12109 Filter
• 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 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence

Abstract

The present invention provides a micro-resonator including a plurality of waveguides forming optic junctions therebetween, with adjacent waveguides having different core permittivities and different cladding permittivities. Adjacent waveguides are mode-matched through adjustments of the core permittivities and the cladding permittivities of the waveguides to reduce or eliminate junction radiation, thereby providing high performance.

Claims

1. A device comprising:

a plurality of waveguide sections, each of said waveguide sections adjacent another waveguide section and forming an optical resonant cavity therebetween, at least one waveguide section having a different cladding permittivity than an adjacent one of said plurality of waveguide sections, and wherein electric field distributions through said adjacent waveguide sections are mode-matched in a direction orthogonal to a desired direction of propagation in the device such that field distributions between waveguide sections are matched so as to reduce coupling to radiation modes within the device thereby improving a Q characteristic of the optical resonant cavity wherein the sections are mode-matched through adjustments of at least one of said waveguide sections core permittivity and said waveguide sections cladding permittivity.

2. The device of claim 1 wherein a first waveguide section has a core permittivity ε

₁ and a cladding permittivity ε

₂ and a second waveguide section has a core permittivity {tilde over (ε

)}₁ and a cladding permittivity {tilde over (ε

)}₂, and wherein said adjacent waveguide sections are mode-matched in accordance with the formula;

ε

₁−

ε

₂={tilde over (ε

)}₁−

{tilde over (ε

)}₂.

3. The device of claim 1 wherein said device is operated with an electric field which is generally parallel to a core-to-cladding interface of said waveguide sections.

4. The device of claim 1 wherein at least one waveguide section comprises a defect layer.

5. The device of claim 4 wherein said device has at least one active region disposed in the defect layer of said device.

6. The device of claim 5 wherein said active region is a gain medium used to form a light source.

7. The device of claim 6 wherein said light source comprises a laser.

8. The device of claim 5 wherein said active region is used for tuning or turning off the resonance.

9. high order filter comprising a plurality of resonators coupled together wherein at least one of such resonators comprises a plurality of waveguide sections with at least one waveguide section having a different cladding permittivity than an adjacent one of said plurality of waveguide sections, and wherein said adjacent waveguide sections are mode-matched in a desired direction of propagation in the filter through adjustments of at least one of said waveguide sections core permittivity and said waveguide sections cladding permittivity such that field distributions between waveguide sections are matched thereby improving a Q characteristic of the filter and reduce coupling to radiation modes within the device which are orthogonal to the desired direction of propagation.

10. The filter of claim 9 wherein a first waveguide section has a core permittivity ε

₁ and a cladding permittivity ε

₂ and a second waveguide section has a core permittivity {tilde over (ε

)}₁ and a cladding permittivity {tilde over (ε

)}₂, and wherein said adjacent waveguide sections are mode-matched in accordance with the formula;

ε

₁−

ε

₂={tilde over (ε

)}₁−

{tilde over (ε

)}₂.

11. The filter of claim 9 wherein said waveguide sections have a shape selected from the group including cylindrical and annular.

12. The filter of claim 9 wherein at least one of said waveguide sections comprise a defect layer.

13. The filter of claim 12 wherein said device has at least one active region disposed in said at least one defect layer of said device.

14. The filter of claim 13 wherein said at least one active region is used for at least one of tuning, detection, and turning off the filter.

15. A device comprising:

a plurality of waveguide sections, each of said waveguide sections having a cylindrical cross-sectional shape and arranged in an axial direction to form an optic junction there between, at least one waveguide section having a different cladding permittivity than an adjacent one of said plurality of waveguide sections, and wherein said adjacent waveguide sections are mode-matched through adjustments of at least one of said waveguide sections core permittivity and said waveguide sections cladding permittivity with each of said plurality of waveguide sections being oriented such that an electric field can propagate in an axial direction through each of said waveguide sections and electric field distributions through said adjacent waveguide sections are mode-matched in a direction orthogonal to the axial direction of propagation in the device so as to reduce coupling to radiation modes within the device thereby improving a Q characteristic of the device.

16. The device of claim 15 wherein a first waveguide section has a core permittivity ε

₁ and a cladding permittivity ε

₂ and a second waveguide section has a core permittivity {tilde over (ε

)}₁ and a cladding permittivity {tilde over (ε

)}₂, and wherein said adjacent waveguide sections are mode-matched in accordance with the formula;

ε

₁−

ε

₂={tilde over (ε

)}₁−

{tilde over (ε

)}₂.

17. The device of claim 15 wherein at least one of said waveguide sections comprises a defect layer.

18. The device of claim 15 wherein said waveguide sections form a diffractive grating.

19. The device of claim 15 wherein said waveguide sections form a resonant cavity.

20. The device of claim 15 operated with an electric field which is generally parallel to a core-to-cladding interface of said waveguide sections.

21. The device of claim 17 wherein said device has at least one active region disposed in the defect layer of said device.

22. The device of claim 21 wherein said active region is a gain medium used to form a light source.

23. The device of claim 22 wherein said light source comprises a laser.

24. The device of claim 18 wherein said active region is used for at least one of tuning and turning off device resonance.

25. A device comprising:

a plurality of waveguide sections, each of said waveguide sections having a shape chosen from the group comprising cylindrical and annular, each of said waveguide section adjacent another waveguide section and forming a radially symmetric optic junction therebetween, at least one waveguide section having at least one of a different core permittivity and a different cladding permittivity than an adjacent one of said plurality of waveguide sections, and wherein said adjacent waveguide sections are mode-matched in a desired direction of propagation in the device through adjustments of at least one of said waveguide sections core permittivity and said waveguide sections cladding permittivity so as to reduce the generation of radiation modes at each optic junction within the device thereby improving a Q characteristic of the device.

26. The device of claim 25 wherein a first waveguide section has a core permittivity ε

₁ and a cladding permittivity ε

₂ and a second waveguide section has a core permittivity {tilde over (ε

)}₁ and a cladding permittivity {tilde over (ε

)}₁, and wherein said adjacent waveguide sections are mode-matched in accordance with the formula;

ε

₁−

ε

₂={tilde over (ε

)}₁−

{tilde over (ε

)}₂.

27. The device of claim 25 wherein at least one waveguide section comprises a defect layer.

28. The device of claim 25 wherein said waveguide sections form a diffractive grating.

29. The device of claim 25 wherein said waveguide sections form a resonant cavity.

30. The device of claim 25 operated with an electric field which is generally parallel to a core-to-cladding interface of said waveguide sections.

31. The device of claim 27 wherein said device has at least one active region disposed in the defect layer of said device.

32. The device of claim 31 wherein said active region is a gain medium used to form a light source.

33. The device of claim 32 wherein said light source comprises a laser.

34. The device of claim 31 wherein said active region is used for at least one of tuning and turning off device resonance.