Microfiber Magnetometer

• US 20100271016A1
• Filed: 04/24/2009
• Published: 10/28/2010
• Est. Priority Date: 04/24/2009
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Barclay, Paul E., Santori, Charles M., Fiorentino, Marco, Fu, Kai-Mei Camilla, Beausoleil, Raymond G.
• Granted Patent: US 8,138,756 B2
• Time in Patent Office: Days
• US Class Current: 324/244.100
• CPC Class Codes: B29D 11/00663 Production of light guides
• CPC Class Codes: G01R 33/032 using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
• CPC Class Codes: G01R 33/323 Detection of MR without the use of RF or microwaves, e.g. force-detected MR, thermally detected MR, MR detection via electrical conductivity, optically detected MR
• CPC Class Codes: Y10S 977/96 Of magnetic property

Abstract

A magnetometer includes a tapered microfiber having a curved portion, an excitation laser in optical communication with the tapered microfiber, and a nanocrystal attached to the curved portion of the tapered microfiber. Laser light emitted from the excitation laser interacts with the nanocrystal to create an emitted photon flux which is monitored to detect a magnetic field passing through the nanocrystal.

Claims

1. A magnetometer comprising:

a tapered microfiber having a curved portion;

an excitation laser configured to be in optical communication with the tapered microfiber; and

a nanocrystal configured to be attached to the curved portion of the tapered microfiber;

in which laser light emitted from the excitation laser is coupled to a first end of the tapered microfiber and interacts with the nanocrystal to create an emitted photon flux which is monitored to detect a magnetic field passing through the nanocrystal.

3. The magnetometer of claim 1, further comprising an adhesive configured to bond the nanocrystal to the curved portion of the tapered microfiber.

4. The magnetometer of claim 1, in which the tapered microfiber has a minimum fiber diameter of less than two times an optical wavelength of the laser light.

5. The magnetometer of claim 1, in which the nanocrystal is a diamond nanocrystal.

6. The magnetometer of claim 5, in which the diamond nanocrystal comprises one or more nitrogen-vacancy defects.

7. The magnetometer of claim 1, further comprising a microwave emitter configured to emit microwave radiation incident on the nanocrystal.

8. The magnetometer of claim 7, in which the microwave emitter is configured to emit microwave radiation whose frequency is swept through a range which includes a frequency resonant with a ground state splitting of the electronic structure of the nanocrystal.

9. The magnetometer of claim 1, further comprising an optical detector configured to be optically coupled a second end of the tapered microfiber and detect the emitted photon flux.

10. The magnetometer of claim 1, further comprising an optical filter configured to be optically interposed between the microfiber and the optical detector such that the optical filter blocks the laser light emitted by the excitation laser from reaching the optical detector.

11. The magnetometer of claim 1, in which the curved portion of the tapered microfiber is a microfiber loop.

12. The magnetometer of claim 1, in which the curved portion of the tapered microfiber is a microfiber dimple.

2. The magnetometer of clam 1, in which the nanocrystal is attached to the curved portion of the tapered microfiber using at least one of:

van der Waals forces and electrostatic forces.

13. A method of forming microfiber magnetometer comprising:

heating and drawing out a continuous optical fiber to form a tapered microfiber segment;

creating a curved portion in the tapered microfiber segment; and

attaching a nanocrystal which exhibits optically detected magnetic resonance to the curved portion of the tapered microfiber segment.

14. The method of claim 13, in which the continuous optical fiber is drawn out to a minimum fiber diameter of less than two times the operating optical wavelength of the tapered microfiber segment.

15. The method of claim 13, further comprising directing optical energy from an excitation source into a first end of the continuous optical fiber and directing an emitted photon flux from a second end of the continuous optical fiber into a photodetector.

16. The method of claim 13, in which the nanocrystal is attached to the curved portion of the tapered microfiber segment by at least one of:

van der Waals forces, electrostatic forces, or adhesive.

17. The method of claim 13, further comprising placing a microwave emitter in proximity to the nanocrystal.

18. The method of claim 13, further comprising creating a loop in the tapered microfiber segment, the loop forming the curved portion.

19. The method of claim 13, further comprising creating a dimple in the tapered microfiber segment by pressing the tapered microfiber segment against a mold and heating the tapered microfiber segment such that the tapered microfiber segment to conforms to the mold geometry.

20. A method for using a microfiber magnetometer for measuring a magnetic field comprises:

directing electromagnetic radiation from an excitation laser through a first end of an fiber optic cable, wherein the fiber optic cable has been tapered down to form a microfiber loop and has a nanocrystal attached to the microfiber loop;

applying microwave radiation to the nanocrystal;

sweeping the microwave radiation through a range of frequencies;

monitoring photon flux emitted by a second end of the fiber optic cable for a reduction in photon flux produced by the nanocrystal;

correlating the reduction in photon flux to an external magnetic field incident on the nanocrystal.