OPTICALLY DETECTED MAGNETIC RESONANCE IMAGING WITH AN ELECTROMAGNETIC FIELD RESONATOR

• US 20170010338A1
• Filed: 02/13/2015
• Published: 01/12/2017
• Est. Priority Date: 02/13/2014
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: Bayat, Khadijeh, Loncar, Marko
• Granted Patent: US 10,359,480 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 1/00 Sampling; Preparing specimens for investigation
• CPC Class Codes: G01N 2201/00 Features of devices classified in G01N21/00
• 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: G01R 33/62 using double resonance G01R33/24 takes precedence
• CPC Class Codes: G02B 1/00 Optical elements characterised by the material of which they are made; Optical coatings for optical elements

Abstract

Measuring a sample includes providing a magnetic field at the sample using an electromagnetic field resonator. The electromagnetic field resonator includes two or more resonant structures at least partially contained within dielectric material of a substrate, at least a first resonant structure configured to provide the magnetic field at the sample positioned in proximity to the first resonant structure. The sample is characterized by an electron spin resonance frequency. A size of an inner area of the first resonant structure and a number of resonant structures included in the electromagnetic field resonator at least partially determine a range of an operating resonance frequency of the electromagnetic field resonator that includes the electron spin resonance frequency. Measuring the sample also includes receiving an output optical signal from the sample generated based at least in part on a magnetic field generated by the electromagnetic field resonator.

Claims

1. An apparatus comprising:

a substrate including a dielectric material;

an electromagnetic field resonator including two or more resonant structures at least partially contained within the dielectric material, at least a first resonant structure configured to provide a magnetic field at a sample positioned in proximity to the first resonant structure, the sample being characterized by an electron spin resonance frequency, wherein a size of an inner area of the first resonant structure and a number of resonant structures included in the electromagnetic field resonator at least partially determine a range of an operating resonance frequency of the electromagnetic field resonator that includes the electron spin resonance frequency; and

an optical coupler positioned in proximity to the first resonant structure, and configured to receive an output optical signal from the sample, the output optical signal being generated based at least in part on a magnetic field generated by the electromagnetic field resonator.

2. The apparatus of claim 1, further comprising a tuning element configured to tune the operating resonance frequency of the electromagnetic field resonator within the range.

3. The apparatus of claim 2, wherein the first resonant structure is configured to at least partially surround the sample within the inner area of the first resonant structure.

4. The apparatus of claim 1, wherein the range of the operating resonance frequency includes at least some microwave frequencies.

5. The apparatus of claim 1, wherein the size of the inner area provides a uniformity of the magnetic field generated by the electromagnetic field resonator within about 10% or less over an area of the sample of about one square millimeter or more.

6. The apparatus of claim 1, wherein the two or more resonant structures comprise two or more split rings.

7. The apparatus of claim 1, wherein the substrate comprises a printed circuit board.

8. The apparatus of claim 1, further comprising an optical coupler configured to receive an output optical signal from the sample, the output optical signal being generated based at least in part on a magnetic field generated by the electromagnetic field resonator.

9. The apparatus of claim 8, wherein the optical coupler is further configured to provide an input optical signal to the sample.

10. The apparatus of claim 1, further including a microwave coupler configured to couple a microwave signal into the electromagnetic field resonator.

11. The apparatus of claim 10, further including a microwave source configured to provide a pulsed microwave signal to the microwave coupler, with a bandwidth of the pulsed microwave signal being within a bandwidth of the electromagnetic field resonator.

12. The apparatus of claim 11, further comprising a tuning element configured to tune the bandwidth of the electromagnetic field resonator.

13. The apparatus of claim 12, wherein the tuning element comprises a material that changes a quality factor of the electromagnetic field resonator.

14. The apparatus of claim 1, wherein the sample comprises diamond, and the electron spin resonance frequency is based on nitrogen-vacancy centers in the diamond.

15. The apparatus of claim 1, wherein the sample comprises a thin-film material.

16. The apparatus of claim 1, wherein:

the first resonant structure is configured to provide a magnetic field at the sample positioned in proximity to a first side of the electromagnetic field resonator; and

the optical coupler is positioned in proximity to a second side of the electromagnetic field resonator, and configured to receive the output optical signal from the sample through an opening defined by the first resonant structure.

17. The apparatus of claim 16, wherein the sample is positioned within a cryogenic chamber.

18. A method for measuring a sample, the method comprising:

providing a magnetic field at the sample using an electromagnetic field resonator including two or more resonant structures at least partially contained within dielectric material of a substrate, at least a first resonant structure configured to provide the magnetic field at the sample positioned in proximity to the first resonant structure, the sample being characterized by an electron spin resonance frequency, wherein a size of an inner area of the first resonant structure and a number of resonant structures included in the electromagnetic field resonator at least partially determine a range of an operating resonance frequency of the electromagnetic field resonator that includes the electron spin resonance frequency; and

receiving an output optical signal from the sample using an optical coupler positioned in proximity to the first resonant structure, the output optical signal being generated based at least in part on a magnetic field generated by the electromagnetic field resonator.