Efficient Fluorescence Detection In Solid State Spin Systems

• US 20140166904A1
• Filed: 06/13/2012
• Published: 06/19/2014
• Est. Priority Date: 06/13/2011
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: Walsworth, Ronald, Le Sage, David
• Granted Patent: US 9,157,859 B2
• Time in Patent Office: Days
• US Class Current: 250/459.1
• CPC Class Codes: G01N 21/645 Specially adapted constructive features of fluorimeters
• CPC Class Codes: G01N 21/6489 Photoluminescence of semiconductors
• CPC Class Codes: G01N 21/87 Investigating jewels G01N21/88 takes precedence
• CPC Class Codes: G01R 33/1284 Spin resolved measurements; Influencing spins during measurements, e.g. in spintronics devices G01R33/093 takes precedence; semiconductor devices using spin polarized carriers H01L29/66984

Abstract

Efficient fluorescence detection is achieved by optically guiding fluorescence light generated by color centers within a sample to photodetectors outside the sample. A fluorescence detection system may use a sample containing one or more fluorescence color centers that emit fluorescent light when irradiated with excitation light from an optical source. The sample has an index of refraction greater than its surrounding medium. The sample may include one or more output faces and further include at least two opposing faces configured to internally reflect the fluorescent light emitted by the fluorescent color centers, and to optically guide the emitted fluorescent light to the one or more output faces. The fluorescence detection system may include one or more optical detector configured to receive fluorescent light emitted through the one or more output faces, and a microwave source configured to manipulate the electronic spin of the fluorescent color centers.

Claims

1. A fluorescence detection system comprising:

an optical source configured to generate excitation light;

a sample containing one or more fluorescence color centers that emit fluorescent light when irradiated with the excitation light from the optical source, wherein the sample has an index of refraction greater than its surrounding medium, said sample comprising at least one output face and further comprising at least two opposing faces configured to internally reflect the fluorescent light emitted by the one or more fluorescent color centers and optically guide the emitted fluorescent light to said at least one output face;

at least one optical detector configured to receive fluorescent light emitted through said at least one output face; and

a microwave source configured to manipulate electronic spin of the one or more fluorescent color centers.

2. The fluorescence detection system of claim 1, wherein the sample is formed of diamond material.

3. The fluorescence detection system of claim 2, wherein the color centers comprise NV (nitrogen vacancy) centers in the diamond material.

4. The fluorescence detection system of claim 1, wherein the sample is in the form of a plate, the plate major faces forming said at least two opposing faces for optically guiding the emitted fluorescent light and the plate further comprising one or more side faces forming said at least one output face.

5. The fluorescence detection system of claim 4, wherein the two opposing faces are parallel to within 10°

.

6. The fluorescence detection system of claim 4, wherein the plate comprises a plurality of side faces and the at least one optical detector is configured to receive fluorescent light emitted from at least two of said plurality of side faces.

7. The fluorescence detection system of claim 6, wherein a plurality of optical detectors are provided, each detector configured to receive light from an associated side face.

8. The fluorescence detection system of claim 1, wherein said at least one optical detector has a size and position relative to said at least one output face to receive at least 75% of fluorescent light emitted through said at least one output face.

9. The fluorescence detection system of claim 1, wherein said at least one optical detector is positioned in contact with said at least one output face either directly or indirectly via a filter.

10. The fluorescence detection system of claim 1, wherein the optical source is a laser or LED tunable to a wavelength of less than 637 nm.

11. The fluorescence detection system of claim 3, wherein the optical source is further configured to optically pump the NV centers so as to prepare the NV spins in an m_s=0 ground state.

12. The fluorescence detection system of claim 1, wherein the fluorescence detection system has a fluorescence collection efficiency of at least 30%.

13. The fluorescence detection system of claim 1, wherein the fluorescence detection system has a fluorescence collection efficiency between 50% and 90%.

14. The fluorescence detection system of claim 1, further comprising a processor configured to determine information about an external field based on the fluorescent light received by the at least one optical detector.

15. The fluorescence detection system of claim 14, wherein said external field is a magnetic field.

16. The fluorescence detection system of claim 14, wherein said external field is an electric field.

17. The fluorescence detection system of claim 15, wherein, wherein the fluorescent detection system has a sensitivity better than 10 nT/√

Hz^1/2.

18. A method of increasing efficiency of fluorescence detection from a sample containing fluorescence color centers, comprising:

placing the sample in a medium whose index of refraction is less compared to the index of refraction of the sample;

constructing and arranging the sample so that fluorescent light emitted by the color centers in response to excitation light is internal reflected by at least two opposing faces of the sample and guided toward an output face of the sample, so that the fluorescent light exiting the sample through said output face can be detected by a detector configured to receive fluorescent light emitted through the output face, and manipulating electronic spin of the color centers.

19. The method of claim 18, wherein the sample is formed of diamond material and the color centers are NV (nitrogen vacancy) centers in the diamond material.