Integrated optical nanoscale probe

• US 9,779,769 B2
• Filed: 11/25/2015
• Issued: 10/03/2017
• Est. Priority Date: 02/19/2014
• Status: Active Grant

• Current Assignee: Infinitum Solutions, Inc.
• Original Assignee: Infinitum Solutions, Inc.
• Inventors: Heidmann, Juergen
• Primary Examiner(s): TANINGCO, MARCUS H
• Application Number:
  US14/952,852
• Publication Number:
  US 20160077167A1
• Time in Patent Office: 678 Days
• CPC Class Codes: G01N 21/64 Fluorescence; Phosphorescence
• CPC Class Codes: G01N 21/6489 Photoluminescence of semiconductors
• CPC Class Codes: G01N 2201/0612 Laser diodes
• CPC Class Codes: G01N 24/10 by using electron paramagnetic resonance G01N24/12 takes precedence
• CPC Class Codes: G01Q 60/08 MFM [Magnetic Force Microscopy] combined with AFM [Atomic Force Microscopy
• CPC Class Codes: G01Q 70/14 Particular materials
• 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: G11B 2005/0021 Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/455 Arrangements for functional testing of heads; Measuring arrangements for heads

Abstract

A diamond probe is suitable to be attached to an Atomic Force Microscope and is created with a tip that incorporates a one or more Nitrogen Vacancy (NV) centers located near the end of the tip. The probe arm acts as an optical waveguide to propagate the emission from the NV center with high efficiency and a beveled end directs excitation light to the NV center and directs photoluminescence light emanating from the NV center into the probe arm. The light source (or a portion of the light source), a detector, as well as an RF antenna, if used, may be mounted to the probe arm. The probe with integrated components enable excitation of photoluminescence in the NV center as well as optically detected Electron Spin Resonance (ODMR) and temperature measurements, and may further serve as a light probe utilizing the physical effect of Stimulated Emission Depletion (STED).

Claims

1. A method comprising:

providing a bias signal to a recording head that includes a write pole to produce a magnetic field from the recording head;

scanning a probe having a probe tip comprising at least one nitrogen vacancy center through the magnetic field produced by the recording head;

providing an excitation radio frequency (RF) field to the at least one nitrogen vacancy center;

producing excitation illumination that is incident on the at least one nitrogen vacancy center;

measuring Optically Detected Spin Resonance (ODMR) by detecting a decrease in a spin dependent photoluminescence in response to the excitation illumination caused by electron spin resonance (ESR) of the at least one nitrogen vacancy center; and

determining a characteristic of the recording head using the ODMR.

2. The method of claim 1, wherein the probe tip comprises a crystal particle and the at least one nitrogen vacancy center is in the crystal particle, further comprising:

focusing the excitation illumination on the crystal particle; and

receiving the spin dependent photoluminescence from the at least one nitrogen vacancy center with a microscope.

3. The method of claim 1, wherein the probe comprises a crystal arm and the probe tip is at a first end of the crystal arm and the at least one nitrogen vacancy center is in the probe tip.

4. The method of claim 3, wherein producing the excitation illumination that is incident on the at least one nitrogen vacancy center comprises introducing the excitation illumination at a second end of the crystal arm that is opposite the first end of the crystal arm, wherein the excitation illumination is guided via total internal reflection through the crystal arm and is reflected into the probe tip.

5. The method of claim 4, wherein introducing the excitation illumination at the second end of the crystal arm is performed without focusing the excitation illumination.

6. The method of claim 4, wherein introducing the excitation illumination at the second end of the crystal arm comprises one of transmitting or reflecting the excitation illumination into the crystal area by a beam splitter that is directly connected to the second end of the crystal arm.

7. The method of claim 6, wherein measuring the ODMR by detecting the decrease in the spin dependent photoluminescence in response to the excitation illumination caused by ESR of the at least one nitrogen vacancy center comprises detecting photoluminescence from the at least one nitrogen vacancy center with a detector that is physical connected to the beam splitter either directly or with a spectral filter disposed between the detector and the beam splitter.

8. The method of claim 4, wherein measuring the ODMR by detecting the decrease in the spin dependent photoluminescence in response to the excitation illumination caused by ESR of the at least one nitrogen vacancy center comprises detecting photoluminescence produced by the at least one nitrogen vacancy center in the probe tip and that is reflected into the crystal arm and extracted through the second end of the crystal arm.

9. The method of claim 8, wherein the photoluminescence extracted through the second end of the crystal arm is detected without focusing the photoluminescence.

10. The method of claim 8, wherein the photoluminescence extracted through the second end of the crystal arm is reflected by the second end of the crystal arm to a detector, and wherein introducing the excitation illumination at the second end of the crystal arm comprises transmitting the excitation illumination into the crystal arm through the second end of the crystal arm.

11. The method of claim 3, wherein the excitation RF field is produced by a radio frequency antenna on the crystal arm.

12. The method of claim 1, wherein the ODMR is measured at varying excitation frequencies of the excitation RF field.

13. The method of claim 1, further comprising providing a plurality of bias signals with different levels to the recording head.

14. The method of claim 1, wherein the recording head further comprises a thermal device and a near-field transducer, the method further comprising:

providing a second bias signal to the thermal device to heat the probe tip using the near-field transducer; and

determining a second characteristic of the recording head using measured ODMR based on heating of the probe tip by the thermal device and the near-field transducer.

15. The method of claim 14, wherein the probe tip is coated with a heat absorption layer.

16. The method of claim 14, wherein the second characteristic of the recording head is a near-field power of the near-field transducer.

17. The method of claim 14, wherein the second characteristic of the recording head is a spatial extent of the near-field transducer.

18. The method of claim 14, further comprising providing a plurality of bias signals with different levels to the thermal device and wherein the second characteristic of the recording head is a function of the heat produced at different levels of bias signals.

19. The method of claim 14, wherein the bias signal provided to the recording head and the second bias signal provided to the thermal device are provided sequentially or serially.

20. An apparatus comprising:

a biasing source configured to provide a bias signal;

a probe card coupled to the biasing source and configured to be connected to a recording head that includes a write pole to provide the bias signal to the recording head that causes the recording head to produce a magnetic field;

a probe having a probe tip comprising at least one nitrogen vacancy center, the probe configured to be scanned through the magnetic field produced by the recording head;

a light source that produces excitation illumination that is incident on the at least one nitrogen vacancy center;

a radio frequency antenna that provides an excitation field to the at least one nitrogen vacancy center;

a detector configured to detect photoluminescence produced by the at least one nitrogen vacancy center in the probe tip;

a processor coupled to the detector and configured to measure Optically Detected Spin Resonance (ODMR) by detecting a decrease in a spin dependent photoluminescence in response to the excitation illumination caused by electron spin resonance (ESR) of the at least one nitrogen vacancy center; and

determine a characteristic of the recording head using the ODMR.

21. The apparatus of claim 20, wherein the probe tip comprises a crystal particle and the at least one nitrogen vacancy center is in the crystal particle, further comprising:

at least one lens configured to focus the excitation illumination on the probe tip and to project photoluminescence produced by the at least one nitrogen vacancy center on the detector.

22. The apparatus of claim 20, wherein the probe comprises a crystal arm and the probe tip is at a first end of the crystal arm and the at least one nitrogen vacancy center is in the probe tip.

23. The apparatus of claim 22, wherein the excitation illumination from the light source is introduced into a second end of the crystal arm that is opposite the first end of the crystal arm, wherein the excitation illumination is guided via total internal reflection through the crystal arm, and, wherein the crystal arm is configured to reflect the excitation illumination into the probe tip.

24. The apparatus of claim 23, wherein the excitation illumination from the light source is introduced into the second end of the crystal arm without focusing optics to focus the excitation illumination.

25. The apparatus of claim 23, further comprising a beam splitter that is directly connected to the second end of the crystal arm, wherein the beam splitter transmits or reflects the excitation illumination from the light source into the crystal arm.

26. The apparatus of claim 25, wherein the detector is physical connected to the beam splitter either directly or with a spectral filter disposed between the detector and the beam splitter.

27. The apparatus of claim 23, wherein the crystal arm is configured to reflect the photoluminescence produced by the at least one nitrogen vacancy center in the probe tip into the crystal arm and the photoluminescence is guided via total internal reflection through the crystal arm and is extracted through the second end of the crystal arm.

28. The apparatus of claim 27, wherein the photoluminescence extracted through the second end of the crystal arm is detected by the detector without intervening focusing optics.

29. The apparatus of claim 27, wherein the second end of the crystal arm is configured to reflect the photoluminescence to the detector, and wherein the excitation illumination from the light source is introduced into the crystal arm by transmitting the excitation illumination through the second end of the crystal arm.

30. The apparatus of claim 22, wherein the radio frequency antenna is on the crystal arm.

31. The apparatus of claim 20, wherein the ODMR is measured at varying excitation frequencies of the excitation field.

32. The apparatus of claim 20, further comprising providing a plurality of bias signals with different levels to the recording head.

33. The apparatus of claim 20, wherein the probe is scanned over a write pole of the recording head and wherein the determined characteristic of the recording head is magnetic field values.

34. The apparatus of claim 20, wherein the recording head further comprises a thermal device and a near-field transducer, the apparatus further comprising:

a second biasing source configured to provide a second bias signal to the thermal device to heat the probe tip using the near-field transducer;

wherein the processor is further configured to determine a second characteristic of the recording head using measured ODMR based on heating of the probe tip by the thermal device and the near-field transducer.

35. The apparatus of claim 34, wherein the probe tip is coated with a heat absorption layer.

36. The apparatus of claim 34, wherein the second characteristic of the recording head is a near-field power of the near-field transducer.

37. The apparatus of claim 34, wherein the second characteristic of the recording head is a spatial extent of the near-field transducer.

38. The apparatus of claim 34, wherein the second biasing source provides a plurality of bias signals with different levels to the thermal device and wherein the second characteristic of the recording head is a function of the heat produced at different levels of bias signals.

39. The apparatus of claim 34, wherein the bias signal provided to the recording head and the second bias signal provided to the thermal device are provided sequentially or serially.