Multicore fiber curvature sensor

• US 7,324,714 B1
• Filed: 04/11/2007
• Issued: 01/29/2008
• Est. Priority Date: 04/11/2007
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Flockhart, Gordon M. H., Cranch, Geoffrey A.
• Primary Examiner(s): Sanghavi; Hemang
• Application Number:
  US11/733,962
• Time in Patent Office: 293 Days
• Field of Search: 385/12, 385/13, 385/37, 385/32, 385/126, 250/227.16, 250/227.19, 250/227.17
• US Class Current: 385/12
• CPC Class Codes: G01B 11/18 using photoelastic elements
• CPC Class Codes: G01D 5/35383 using multiple sensor devices using multiplexing techniques
• CPC Class Codes: G02B 6/02042 Multicore optical fibres
• 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: G02B 6/29319 With a cascade of diffractive elements or of diffraction operations forming interferometer by splitting and recombining G02B6/29347 - G02B6/29358
• CPC Class Codes: G02B 6/29356 Interference cavity within a single light guide, e.g. between two fibre gratings G02B6/29347 - G02B6/2935 take precedence; evanescent coupling to a resonator cavity G02B6/29335
• CPC Class Codes: G02B 6/29358 Multiple beam interferometer external to a light guide, e.g. Fabry-Pérot, etalon, VIPA plate, OTDL plate, continuous interferometer, parallel plate resonator G02B6/29347, G02B6/29349, G02B6/2935, G02B6/29361 take precedence; resonator evanescently coupled to light guide G02B6/29335

Abstract

An apparatus includes a multicore fiber including three cores. The three cores include two pairs of cores, each pair of cores lying in a plane. The planes of the two pairs of cores are non-coplanar. The multicore fiber includes a rosette, the rosette including three coplanar interferometers. Each interferometer of the three interferometers are located in a respective core of the three cores. Each interferometer includes a first reflector and a second reflector. The first reflectors of the rosette are coplanar. The second reflectors of the rosette are coplanar.

Claims

1. An apparatus comprising:

a multicore fiber comprising three cores, said three cores comprising two pairs of cores, each pair of cores lying in a plane, said planes of the two pairs of cores being non-coplanar,

said multicore fiber comprising a rosette, said rosette comprising three coplanar interferometers, each interferometer of said three interferometers being located in a respective core of said three cores, said each interferometer comprising a first reflector and a second reflector, said first reflectors of said rosette being coplanar, said second reflectors of said rosette being coplanar.

2. The apparatus according to claim 1, wherein, for said each interferometer, said first reflector comprises a first fiber Bragg grating, said second reflector comprises a second fiber Bragg grating, said first fiber Bragg grating and said second fiber Bragg grating comprise a substantially similar fiber Bragg resonance.

3. The apparatus according to claim 2, further comprising a reference reflector adjacent to said each interferometer, said reference reflector comprising a third fiber Bragg grating comprising a second fiber Bragg resonance outside a bandwidth of said first fiber Bragg resonance.

4. The apparatus according to claim 2, further comprising:

a reference reflector within said each interferometer, said reference reflector comprising a third fiber Bragg grating comprising a second fiber Bragg resonance outside a bandwidth of said first fiber Bragg resonance.

5. The apparatus according to claim 1, wherein said three cores comprise substantially similar material.

6. The apparatus according to claim 1, further comprising a first section and a second section, said rosette comprising a first rosette and a second rosette, said first section comprising said three cores tracing a helical path centered about the central fiber axis and said second section comprising said three cores parallel to each other and the central fiber axis, at least one of said first section comprising said first rosette and said second section comprising said second rosette.

7. The apparatus according to claim 1, further comprising:

a path-matching interferometer communicating with said multicore fiber.

8. The apparatus according to claim 7, wherein said path-matching interferometer comprises one of a Mach-Zehnder interferometer, a Michelson interferometer, and a low-finesse Fabry-Perot interferometer.

9. The apparatus according to claim 8, wherein said Michelson interferometer comprises plurality of Faraday rotator mirrors.

10. The apparatus according to claim 1, further comprising one of a continuous wave light source and a pulsed broadband light source.

11. The apparatus according to claim 10, wherein said continuous wave light source comprises one of an erbium light source, a praseodymium light source, a semiconductor optical amplifier, a super continuum light source, and a super luminescent diode, and wherein said pulsed broadband light source comprises one of a semiconductor optical amplifier, a mode locked laser, and a switched super luminescent diode.

12. A method comprising:

coupling launched light to a multicore fiber comprising three cores, the three cores comprising two pairs of cores, each pair of cores comprising a plane, the planes of the two pairs of cores being non-coplanar, the multicore fiber comprising a rosette, the rosette comprising three interferometers, each interferometer of the three interferometers being located in a respective core of the three cores, each interferometer comprising a first reflector and a second reflector, the first reflectors of the rosette being coplanar, the second reflectors of the rosette being coplanar;

receiving reflected light from the interferometers; and

demultiplexing the received reflected light to extract interferometric signals from the three interferometers.

13. The method according to claim 12, further comprising:

transmitting a beam from a light source into a path-matching interferometer;

transmitting a beam from the path-matching interferometer;

splitting the beam transmitted from the path-matching interferometer into at least three paths;

passing the three paths through a splitter to separate the launched light from the reflected light.

14. The method according to claim 13, wherein said passing the three paths through a splitter to separate the launched light from the reflected light comprises passing the three paths using one of a circulator and a coupler.

15. The method according to claim 12, said demultiplexing the received reflected light to extract interferometric signals from the three coplanar interferometers comprises:

spectrally separating the received light using a wavelength demultiplexer into wavelength channels; and

transmitting the wavelength channels to respective detectors.

16. The method according to claim 15, said demultiplexing the received reflected light to extract interferometric signals from the three interferometers comprises:

separating the light at each wavelength using a time division demultiplexer into a plurality of time channels, each time channel of the plurality of time channels comprising a respective interferometric signal from a respective interferometer of the three interferometers.

17. The method according to claim 12, said demultiplexing the received reflected light to extract interferometric signals from the three interferometers comprises:

separating the received light from the three interferometers using a time division demultiplexer into a plurality of time channels, each time channel of the plurality of time channels comprising a respective interferometric signal from a respective interferometer of the coplanar interferometers.

18. The method according to claim 13, wherein the light source comprises one of a continuous wave light source and a pulsed broadband light source.

19. The apparatus according to claim 18, wherein the continuous wave light source comprises one of an erbium light source, a praseodymium light source, a semiconductor optical amplifier, a super continuum light source, and a super luminescent diode, and wherein the pulsed broadband light source comprises one of a semiconductor optical amplifier, a mode locked laser, and a switched super luminescent diode.