Compression-tuned Bragg grating and laser

• US 6,363,089 B1
• Filed: 10/19/2000
• Issued: 03/26/2002
• Est. Priority Date: 12/04/1998
• Status: Expired due to Term

• Current Assignee: Weatherford Technology Holdings, LLC (Weatherford International PLC)
• Original Assignee: Cidra Sarl (Nordic Cultural & Educational Foundation)
• Inventors: Kersey, Alan D., Fernald, Mark R., Bailey, Timothy J., Putnam, Martin A., Davis, Michael A., Sanders, Paul E., Brucato, Robert N., Sullivan, James M., Miller, Matthew B.
• Primary Examiner(s): Scott, Jr., Leon
• Application Number:
  US09/691,997
• Time in Patent Office: 523 Days
• Field of Search: 372/6, 372/20, 372/102, 372/64, 372/92, 372/96, 385/37, 385/24, 359/568, 359/569
• US Class Current: 372/20
• CPC Class Codes: G02B 6/0218 using mounting means, e.g. by using a combination of materials having different thermal expansion coefficients
• 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
• CPC Class Codes: G02F 1/0115 in optical fibres
• CPC Class Codes: G02F 1/0128 based on electro-mechanical, magneto-mechanical, elasto-optic effects
• CPC Class Codes: G02F 2201/307 Reflective grating, i.e. Bragg grating

Abstract

A compression-tuned bragg grating includes a tunable optical element 20,600 which includes either an optical fiber 10 having at least one Bragg grating 12 impressed therein encased within and fused to at least a portion of a glass capillary tube 20or a large diameter waveguide grating 600 having a core and a wide cladding. Light 14 is incident on the grating 12 and light 16 is reflected at a reflection wavelength λ1. The tunable element 20,600 is axially compressed which causes a shift in the reflection wavelength of the grating 12 without buckling the element. The shape of the element may be other geometries (e.g., a “dogbone” shape) and/or more than one grating or pair of gratings may be used and more than one fiber 10 or core 612 may be used. At least a portion of the element may be doped between a pair of gratings 150,152, to form a compression-tuned laser or the grating 12 or gratings 150,152 may be constructed as a tunable DFB laser. Also, the element 20 may have an inner tapered region 22 or tapered (or fluted) sections 27. The compression may be done by a PZT, stepper motor or other actuator or fluid pressure.

Claims

1. A compression-tuned optical device comprising:

an optical waveguide including an inner core disposed within an outer cladding and a grating disposed within the inner core, the grating reflecting a first reflection wavelength of light back along the inner core and propagating remaining wavelengths of light through the grating, the optical waveguide including a pair of opposing surfaces; and

a compressing device engaging the opposing surfaces of the optical waveguide for compressing the opposing surfaces towards each other to tune the grating to change the reflection wavelength of light reflected back along the inner core.

2. The apparatus of claim 1 wherein the optical waveguide has outer dimensions along perpendicular axial and transverse directions, the outer dimension being at least 0.3 mm along the transverse direction.

3. The apparatus of claim 1 wherein at least a portion of the optical waveguide has a transverse cross-section that is contiguous and comprises a substantially homogeneous material.

4. The apparatus of claim 3 wherein the homogeneous material comprises a glass material.

5. The apparatus of claim 1 wherein the optical waveguide comprises:

an optical fiber, having the grating embedded therein; and

a tube, having the optical fiber and the grating encased therein along a longitudinal axis of the tube, the tube being fused to at least a portion of the fiber.

6. The apparatus of claim 1 wherein at least a portion of the optical waveguide comprises a generally cylindrical shape, having a diameter being at least 0.3 mm.

7. The apparatus of claim 1, wherein the optical wavelength has at least one pair of gratings disposed therein and at least a portion of the optical waveguide is doped with a rare-earth dopant between the pair of gratings to form a laser.

8. The apparatus of claim 1, wherein at least a portion of the optical waveguide is doped with a rare-earth dopant where the grating is located and the grating is configured to form a DFB laser.

9. The apparatus of claim 1 wherein the grating has a characteristic wavelength and wherein the optical waveguide comprises a shape that provides a predetermined sensitivity to a shift in the wavelength due to a change in force on the optical waveguide.

10. The apparatus of claim 9 wherein the shape of the optical waveguide comprises a generally dogbone shape.

11. The apparatus of claim 1, wherein the compressing device comprises an actuator mechanically engaging the opposing surfaces of the optical waveguide.

12. The apparatus of claim 1, wherein an outer dimension of the optical waveguide along an axial direction is greater than an outer dimension of the optical waveguide along an transverse direction.

13. The apparatus of claim 1, wherein the inner core is a single mode core.

14. A method for wavelength-tuning an optical device, comprising:

providing an optical waveguide including an inner core disposed within an outer cladding and a grating disposed within the inner core, the grating reflecting a first reflection wavelength of light back along the inner core and propagating remaining wavelengths of light through the grating, the optical waveguide including a pair of opposing surfaces; and

compressing the opposing surfaces of the optical waveguide towards each other to tune the grating to change the reflection wavelength of light reflected back along the inner core.

15. The method of claim 14 wherein the optical waveguide has outer dimensions along perpendicular axial and transverse directions, the outer dimension being at least 0.3 mm along the transverse direction.

16. The method of claim 14 wherein at least a portion of the optical waveguide has a transverse cross-section that is contiguous and comprises a substantially homogeneous material.

17. The method of claim 16 wherein the homogeneous material comprises a glass material.

18. The method of claim 14 wherein the optical waveguide comprises:

an optical fiber, having the grating embedded therein; and

a tube, having the optical fiber and the grating encased therein along a longitudinal axis of the tube, the tube being fused to at least a portion of the fiber.

19. The method of claim 14 wherein at least a portion of the optical waveguide comprises a generally cylindrical shape, having a diameter being at least 0.3 mm.

20. The method of claim 14, wherein the optical wavelength has at least one pair of gratings disposed therein and at least a portion of the optical waveguide is doped with a rare-earth dopant between the pair of gratings to form a laser.

21. The method of claim 14, wherein at least a portion of the optical waveguide is doped with a rare-earth dopant where the grating is located and the grating is configured to form a DFB laser.

22. The method of claim 14 wherein the grating has a characteristic wavelength and wherein the optical waveguide comprises a shape that provides a predetermined sensitivity to a shift in the wavelength due to a change in force on the optical waveguide.

23. The method of claim 22 wherein the shape of the optical waveguide comprises a generally dogbone shape.

24. The method of claim 14, wherein the compressing device comprises an actuator mechanically engaging the opposing surfaces of the optical waveguide.

25. The method of claim 14, wherein an outer dimension of the optical waveguide along an axial direction is greater than an outer dimension of the optical waveguide along an transverse direction.

26. The method of claim 14, wherein the inner core is a single mode core.