Micro piezo-optic composite transducers and fabrication methods

• US 20050253050A1
• Filed: 05/13/2004
• Published: 11/17/2005
• Est. Priority Date: 05/13/2004
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Koste, Glen Peter, Nielsen, Matthew Christian, Seeley, Charles Erklin
• Granted Patent: US 7,030,366 B2
• Time in Patent Office: Days
• US Class Current: 250/227.140
• CPC Class Codes: G01B 11/18 using photoelastic elements
• CPC Class Codes: G01M 11/086 Details about the embedment of the optical fiber within the DUT
• CPC Class Codes: G01M 5/0041 by determining deflection or stress
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection
• CPC Class Codes: G01R 15/24 using light-modulating devices
• CPC Class Codes: G02B 6/022 using mechanical stress, e.g. tuning by compression or elongation, special geometrical shapes such as "dog-bone" or taper G02B6/02204 takes precedence; optical modulation using photo-elastic effect G02F1/0131

Abstract

A micro piezo-optic composite transducer comprises: dielectric material; electrodes situated over opposing surfaces of the dielectric material; an optical fiber embedded in the dielectric material, the optical fiber configured to have a wavelength response as a function of material strain; and piezoelectric fibers embedded in the dielectric material and situated on opposing sides of the optical fiber.

Claims

1. A micro piezo-optic composite transducer comprising:

dielectric material;

electrodes situated over opposing surfaces of the dielectric material;

an optical fiber embedded in the dielectric material, the optical fiber configured to have a wavelength response as a function of material strain;

piezoelectric fibers embedded in the dielectric material and situated on opposing sides of the optical fiber.

2. The transducer of claim 1 wherein the electrodes comprise interdigitated electrodes and wherein at least two piezoelectric fibers are embedded on each opposing side of the optical fiber.

3. The transducer of claim 2 wherein the lengths of the piezoelectric fibers are substantially parallel with respect to the lengths of the optical fiber and substantially perpendicular with respect to the interdigitated electrodes.

4. The transducer of claim 3 wherein the optical fiber includes a Fabry-Perot cavity.

5. The transducer of claim 3 wherein the optical fiber includes a grating.

6. The transducer of claim 5 wherein the grating comprises a Bragg grating.

7. The transducer of claim 5 wherein the grating comprises a long period grating.

8. The transducer of claim 3 wherein the piezoelectric fibers are ceramic fibers or single crystal fibers.

9. The transducer of claim 3 wherein the dielectric layer comprises a polymer, the optical fiber comprises glass, and the piezoelectric fibers comprise fibers selected from the group consisting of ceramic fibers, single crystal fibers, or combinations thereof.

42. The transducer of claim 3 wherein the optical fiber comprises a material selected from the group consisting of glass and polymer.

10. A micro piezo-optic composite transducer comprising:

dielectric material;

interdigitated electrodes situated over opposing surfaces of the dielectric material;

an optical fiber embedded in the dielectric material, the optical fiber including a Bragg grating and configured to have a wavelength response as a function of material strain;

piezoelectric fibers embedded in the dielectric material and situated on opposing sides of the optical fiber, wherein the lengths of the piezoelectric fibers are substantially parallel with respect to the lengths of the optical fiber and substantially perpendicular with respect to the interdigitated electrodes.

11. The transducer of claim 10 wherein the dielectric layer comprises a polymer, the optical fiber comprises glass, and the piezoelectric fibers comprise fibers selected from the group consisting of ceramic fibers, single crystal fibers, or combinations thereof.

12. A sensing system comprising:

a micro piezo-optic composite transducer comprising;

dielectric material, electrodes situated over opposing surfaces of the dielectric material, an optical fiber embedded in the dielectric material, the optical fiber configured to have a wavelength response as a function of material strain, and piezoelectric fibers embedded in the dielectric material and situated on opposing sides of the optical fiber, selected ones of the interdigitated electrodes being coupled to selected ends of the resistor;

a processor for monitoring changes in light transmitted or reflected by the optical fiber and using the changes to obtain signal information, wherein the signal information comprises signal information selected from the group consisting of current information, voltage information, and combinations thereof.

13. The sensing system of claim 12 further comprising a resistor, wherein the micro piezo-optic composite transducer is electrically coupled to the resistor.

14. The sensing system of claim 12 wherein the electrodes comprise interdigitated electrodes and wherein at least two piezoelectric fibers are embedded on each opposing side of the optical fiber.

15. The sensing system of claim 14 wherein the lengths of the piezoelectric fibers are substantially parallel with respect to the lengths of the optical fiber and substantially perpendicular with respect to the interdigitated electrodes.

16. The sensing system of claim 15 wherein the optical fiber includes a Fabry-Perot cavity.

17. The sensing system of claim 15 wherein the optical fiber includes a grating.

18. The sensing system of claim 17 wherein the grating comprises a Bragg grating.

19. The sensing system of claim 17 wherein the grating comprises a long period grating.

20. The sensing system of claim 15 wherein the piezoelectric fibers are ceramic fibers or single crystal fibers.

21. The sensing system of claim 15 wherein the dielectric layer comprises a polymer, the optical fiber comprises glass, and the piezoelectric fibers comprise fibers selected from the group consisting of ceramic fibers, single crystal fibers, or combinations thereof.

22. The sensing system of claim 12 wherein the micro piezo-optic composite transducer comprises a plurality of micro piezo-optic composite transducers, each micro piezo-optic composite transducer including the optical fiber.

23. The sensing system of claim 22 wherein the electrodes comprise interdigitated electrodes and wherein at least two piezoelectric fibers are embedded on each opposing side of the optical fiber.

24. The sensing system of claim 23 wherein the optical fiber includes at least one Bragg grating situated in at least one of the micro piezo-optic composite transducers.

25. The sensing system of claim 23 wherein the optical fiber includes a plurality of Bragg gratings, each situated in respective ones of the micro piezo-optic composite transducers.

26. The sensing system of claim 25 wherein at least two of the plurality of Bragg gratings have different modulation refractive index periods.

27. A sensing system comprising:

an optical fiber;

a plurality of micro piezo-optic composite transducers each comprising;

dielectric material, interdigitated electrodes situated over opposing surfaces of the dielectric material, the optical fiber embedded in the dielectric material and configured to have a wavelength response as a function of material strain, and piezoelectric fibers embedded in the dielectric material and situated on opposing sides of the optical fiber;

a processor for monitoring changes in light transmitted or reflected by the optical fiber and using the changes to obtain signal information from the plurality of micro piezo-optic composite transducers, wherein the signal information comprises signal information selected from the group consisting of current information, voltage information, and combinations thereof.

28. The sensing system of claim 27 wherein the lengths of the piezoelectric fibers are substantially parallel with respect to the lengths of the optical fiber and substantially perpendicular with respect to the interdigitated electrodes.

29. The sensing system of claim 28 wherein the piezoelectric fibers are ceramic fibers or single crystal fibers.

30. The sensing system of claim 28 wherein the optical fiber includes a Fabry-Perot cavity.

31. The sensing system of claim 28 wherein the optical fiber includes at least one grating situated in at least one of the micro piezo-optic composite transducers.

32. The sensing system of claim 31 wherein the at least one grating comprises a Bragg grating, a long period grating, or combinations thereof.

33. The sensing system of claim 28 wherein the optical fiber includes a plurality of Bragg gratings, each situated in a respective one of the micro piezo-optic composite transducers.

34. The sensing system of claim 33 wherein at least two of the plurality of Bragg gratings have different modulation refractive index periods.

35. A method for fabricating a micro piezo-optic composite transducer comprising:

(a) positioning a first portion of dielectric material on a support surface, the first portion of dielectric material including interdigitated electrodes coated thereon and facing towards the support surface;

(b) positioning an optical fiber configured to have a wavelength response as a function of material strain and piezoelectric fibers on the first portion of dielectric material with the piezoelectric fibers situated on opposing sides of the optical fiber;

(c) positioning a second portion of dielectric material over the optical fiber and piezoelectric fibers, the second portion of dielectric material including interdigitated electrodes coated thereon and facing away from the support surface;

(d) curing the first and second portions of dielectric material.

36. The method of claim 35 wherein the positioning in (a), (b), and (c) is performed in a manner so that the lengths of the piezoelectric fibers are substantially parallel with respect to the lengths of optical fiber and substantially perpendicular were respect to the interdigitated electrodes.

37. The method of claim 36 wherein the optical fiber includes a Fabry-Perot cavity.

38. The method of claim 35 wherein the optical fiber includes a grating.

39. The method of claim 38 wherein the grating comprises a Bragg grating.

40. The method of claim 39 wherein the grating comprises a long period grating.

41. The method of claim 35 wherein the dielectric layer comprises a polymer, the optical fiber comprises glass, and the piezoelectric fibers comprise fibers selected from the group consisting of ceramic fibers, single crystal fibers, or combinations thereof.