Apparatus and method for resonance magneto-optical defect center material pulsed mode referencing

• US 10,228,429 B2
• Filed: 03/24/2017
• Issued: 03/12/2019
• Est. Priority Date: 03/24/2017
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Bruce, Gregory Scott, Manickam, Arul, Kaup, Peter G.
• Primary Examiner(s): Bonnette, Rodney A
• Application Number:
  US15/468,289
• Publication Number:
  US 20180275221A1
• Time in Patent Office: 718 Days
• CPC Class Codes: G01R 33/032 using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
• CPC Class Codes: G01R 33/26 using optical pumping

Abstract

The present disclosure relates to apparatuses and methods for stimulating a magneto-optical defect material with defect centers in a magnetic detection system using a stimulation process to significantly increase magnetic sensitivity of the detection system. The system utilizes a modified Ramsey pulse sequence pair or a shifted magnetometry adapted cancellation (SMAC) pair to detect and measure the magnetic field acting on the system resulting in mitigation of low-frequency noise sources to provide improved sensor sensitivity. For a SMAC pair measurement, two different values of tau are used as well as two different values of the microwave pulse width.

Claims

1. A system for magnetic detection, comprising:

a magneto-optical defect center material comprising a plurality of defect centers and lattice oriented subsets;

a radio frequency (RF) excitation source configured to provide RF excitation to the magneto-optical defect center material;

an optical excitation source configured to provide optical excitation to the magneto-optical defect center material;

an optical detector configured to receive an optical signal emitted by the magneto-optical defect center material;

a bias magnet configured to separate RF resonance responses of the lattice oriented subsets of the magneto-optical defect center material;

and

a controller configured to;

control the optical excitation source and the RF excitation source to apply a first pulse sequence to the magneto-optical defect center material, the first pulse sequence comprising a first optical excitation pulse, a first pair of RF excitation pulses separated by a first time period, and a second optical excitation pulse to the magneto-optical defect center material;

control the optical excitation source and the RF excitation source to apply a second pulse sequence to the magneto-optical defect center material, the second pulse sequence comprising a third optical excitation pulse, a second pair of RF excitation pulses separated by a second time period, and a fourth optical excitation pulse to the magneto-optical defect center material, wherein a pulse width of the first pair of RF excitation pulses is different than a pulse width of the second pair of RF excitation pulses, and wherein first time period is different than the second time period;

receive a first light detection signal from the optical detector based on an optical signal emitted by the magneto-optical defect center material due to the first pulse sequence;

receive a second light detection signal from the optical detector based on an optical signal emitted by the magneto-optical defect center material due to the second pulse sequence; and

compute a combined measurement based on a difference between a measured value of the first light detection signal and a measured value of the second light detection signal wherein the slope of the combined measurement is greater than the slope of the measured value of the first and second light detection signals.

2. The system of claim 1, wherein an RF excitation frequency used for the first pair of RF excitation pulses and the second pair of RF excitation pulses is associated with an axis of a defect center of the magneto-optical defect center material.

3. The system of claim 1, wherein the controller is further configured to compute a change in an external magnetic field acting on the magneto-optical defect center material based on the combined measurement.

4. The system of claim 1, wherein the second pair of RF excitation pulses of the first pulse sequence are applied at a frequency detuned from a resonance frequency of the magneto-optical defect center material.

5. The system of claim 1, wherein the pulse width of the second pair of RF excitation pulses is associated with a fluorescence null point of the magneto-optical defect center material.

6. The system of claim 1, wherein the second time period is associated with a fluorescence null point of the magneto-optical defect center material.

7. The system of claim 1, wherein the pulse width of the second pair of RF excitation pulses and the second time period is associated with a fluorescence null point of the magneto-optical defect center material.

8. The system of claim 7, wherein the pulse width of the first pair of RF excitation pulses and the first time period is associated with a fluorescence low point of the magneto-optical defect center material.

9. The system of claim 1, wherein the RF excitation source is a microwave antenna.

10. The system of claim 1, wherein the controller is configured to apply the first pair of RF excitation pulses followed by the second pair of RF excitation pulses.

11. The system of claim 1, wherein the bias magnet is one of a permanent magnet, a magnet field generator, or a Halbach set of permanent magnets.

12. A method for magnetic detection using a magneto-optical defect center material comprising a plurality of defect centers, the method comprising:

applying a first pulse sequence to the magneto-optical defect center material, the first pulse sequence comprising a first optical excitation pulse, using an optical excitation source, a first pair of RF excitation pulses separated by a first time period using a radio frequency (RF) excitation source, and a second optical excitation pulse to the magneto-optical defect center material using the optical excitation source;

applying a second pulse sequence to the magneto-optical defect center material, the second pulse sequence comprising a third optical excitation pulse, using the optical excitation source, a second pair of RF excitation pulses separated by a second time period using the RF excitation source, and a fourth optical excitation pulse to the magneto-optical defect center material, using the optical excitation source, wherein a pulse width of the first pair of RF excitation pulses is different than a pulse width of the second pair of RF excitation pulses, and wherein first time period is different than the second time period;

receiving a first light detection signal, using an optical detector, based on an optical signal emitted by the magneto-optical defect center material due to the first pulse sequence;

receive a second light detection signal, using the optical detector, based on an optical signal emitted by the magneto-optical defect center material due to the second pulse sequence; and

computing a combined measurement based on a difference between a measured value of the first light detection signal and a measured value of the second light detection signal.

13. The method of claim 12, wherein an RF excitation frequency used for the first pair of RF excitation pulses and the second pair of RF excitation pulses is associated with an axis of a defect center of the magneto-optical defect center material.

14. The method of claim 12, further comprising computing a change in an external magnetic field acting on the magneto-optical defect center material based on the combined measurement.

15. The method of claim 12, wherein the second pair of RF excitation pulses of the first pulse sequence are applied at a frequency detuned from a resonance frequency of the magneto-optical defect center material.

16. The method of claim 12, wherein the pulse width of the second pair of RF excitation pulses is associated with a fluorescence null point of the magneto-optical defect center material.

17. The method of claim 12, wherein the second time period is associated with a fluorescence null point of the magneto-optical defect center material.

18. The method of claim 12, wherein the pulse width of the second pair of RF excitation pulses and the second time period is associated with a fluorescence null point of the magneto-optical defeat center material.

19. The method of claim 18, wherein the pulse width of the first pair of RF excitation pulses and the first time period is associated with a fluorescence low point of the magneto-optical defect center material.defect center material.

20. The method of claim 12, wherein the first pair of RF excitation pulses is applied followed by the second pair of RF excitation pulses.

21. A magnetic detection system comprising:

a defect center material responsive to an applied magnetic field;

a radio frequency (RF) emitter operational to provide a first RF pulse sequence separated by at least one pause, said RF emitter operational to provide a second RF pulse sequence that is different from the first RF pulse sequence;

a detector operational to measure a fluorescence of the defect center material in conjunction with the first RF pulse sequence and the second RF pulse sequence, thereby providing a first measurement curve and a second measurement curve affected by the applied magnetic field, respectfully; and

a control circuit connected to the detector and operational to determine a difference between the first measurement curve and the second measurement curve to obtain greater sensitivity to variations in the applied magnetic field.

22. The system of claim 21, wherein the first RF pulse sequence and the second RF pulse sequence are applied at a frequencies detuned from a resonance frequency of the defect center material.

23. The system of claim 21, wherein the first RF pulse sequence is applied followed by the second RF pulse sequence.

24. The system of claim 21, wherein the defect center material is a nitrogen vacancy diamond.

25. The system of claim 21, wherein the defect center material is Silicon Carbide (SiC).

26. A method for detecting a magnetic field comprising:

emitting a first RF pulse sequence separated by at least one pause, using an RF emitter to a defect center material;

emitting a second RF pulse sequence that is different from the first RF pulse sequence, using the RF emitter, to the defect center material;

measure a fluorescence of the defect center material in conjunction with the first RF pulse sequence and the second RF pulse sequence, using a detector;

providing a first measurement curve and a second measurement curve of the measured fluorescence of the defect center material affected by the applied magnetic field, respectfully for the first RF pulse sequence and the second RF pulse sequence; and

determine a difference between the first measurement curve and the second measurement curve to obtain greater sensitivity to variations in the applied magnetic field.

27. The method of claim 26 wherein determining the difference between the first measurement curve and the second measurement curve is performed by a control circuit.

28. The method of claim 26, wherein the first RF pulse sequence and the second RF pulse sequence are applied at a frequency detuned from a resonance frequency of the defect center material.

29. The method of claim 26, wherein the first RF pulse sequence is emitted followed by the second RF pulse sequence.

30. The method of claim 26, wherein the defect center material is a nitrogen vacancy diamond.

31. The method of claim 26, wherein the defect center material is Silicon Carbide (SiC).

32. A system for magnetic detection, comprising:

a magneto-optical defect center material comprising a plurality of defect centers;

a means of providing RF excitation to the magneto-optical defect center material;

a means of providing optical excitation to the magneto-optical defect center material;

a means of receiving an optical signal emitted by the magneto-optical defect center material;

a means of providing a bias magnetic offset to distinguish response curves of different lattice orientation subsets of the magneto-optical defect center material;

and

a means of controlling the provided RF excitation and provided optical excitation to;

apply a first pulse sequence to the magneto-optical defect center material, the first pulse sequence comprising a first optical excitation pulse, a first pair of RF excitation pulses separated by a first time period, and a second optical excitation pulse to the magneto-optical defect center material;

control the optical excitation source and the RF excitation source to apply a second pulse sequence to the magneto-optical defect center material, the second pulse sequence comprising a third optical excitation pulse, a second pair of RF excitation pulses separated by a second time period, and a fourth optical excitation pulse to the magneto-optical defect center material, wherein a pulse width of the first pair of RF excitation pulses is different than a pulse width of the second pair of RF excitation pulses, and wherein first time period is different than the second time period;

receive a first light detection signal from the optical detector based on an optical signal emitted by the magneto-optical defect center material due to the first pulse sequence;

receive a second light detection signal from the optical detector based on an optical signal emitted by the magneto-optical defect center material due to the second pulse sequence; and

compute a combined measurement based on a difference between the measured value of the first light detection signal and a measured value of the second light detection signal.