Device integrated with scanning probe for optical nanofocusing and near-field optical imaging

1. A method for generating a high-intensity light source at a probe tip, the method comprising:

exciting a TM 0 mode of a surface plasmon polariton (SPP) in a sharp-tip metal nanowire (AgNW) waveguide with a linearly-polarized mode (LP 01 ) in a tapered optical fiber (OF); and

compressing the TM 0 mode through a chemically-sharpened taper to a tip apex of the sharp-tip silver nanowire (AgNW).

2. The method according to claim 1 , further comprising:

selectively exciting the TM 0 mode by physically separating coupling regions for the TM 0 mode and a HE 1 mode.

3. The method according to claim 2 , wherein the TM 0 mode has a higher effective mode index than other SPP modes, and incident light in the tapered optical fiber runs into a phase-matching region for the TM 0 mode first, and uncoupled light remaining in the tapered optical fiber propagates into a phase-matching region for the HE 1 mode.

4. The method according to claim 1 , wherein an angle of the tapered optical fiber is 6° to 12°.

5. The method according to claim 1 , wherein the sharp-tip nanowire protrudes 1 μm to 2 μm from a tip of the tapered optical fiber and the sharp-tip silver nanowire has a tip angle of 30° to 50°.

6. The method according to claim 1 , further comprising:

removing low-k components by inserting a k-space filter into an optical path;

focusing high-k information with an objective lens to form a ring pattern at an image plane; and

sending the focused high-k information into a charge-coupled device (CCD) of a spectrometer for analysis.

7. A probe comprising:

a tapered optical fiber (OF) configured to excite a TM 0 mode of a surface plasmon polariton (SPP);

a sharp-tip metal nanowire waveguide arranged on a sidewall of the tapered optical fiber; and

wherein a taper to a tip apex of the sharp-tip nanowire is configured to compress the TM 0 mode.

8. The probe of claim 7 , wherein the sharp-tip metal nanowire is a silver nanowire.

9. The probe of claim 7 , wherein the taper to the tip apex of the sharp-tip nanowire is chemically-sharpened.

10. The probe of claim 7 , wherein the TM 0 mode is selectively excited by physically separating coupling regions for the TM 0 mode and a HE 1 mode.

11. The probe of claim 10 , wherein the TM 0 mode has a higher effective mode index than other SPP modes, and incident light in the tapered optical fiber runs into a phase-matching region for the TM 0 mode first, and uncoupled light remaining in the tapered optical fiber propagates into a phase-matching region for the HE 1 mode.

12. The probe of claim 7 , wherein an angle of the tapered optical fiber is 7° to 12°.

13. The probe of claim 7 , wherein the sharp-tip metal nanowire protrudes 1 μm to 2 μm from a tip of the tapered optical fiber and the sharp-tip silver nanowire has a tip angle of 30° to 50°.

14. The probe of claim 7 , wherein the sharp-tip silver nanowire has a diameter of 100 nm to 300 nm, and an excitation wavelength is 532 nm.

15. The probe of claim 7 , wherein the tapered optical fiber includes a gold electrode partially covering the optical fiber for electrically connecting the metal nanowire for imaging.

16. The probe of claim 7 , wherein the probe is used Raman spectroscopy imaging, photocurrent imaging, UV-VIS imaging, scanning probe microscopes, atomic force microscopes and/or scanning tunneling microscopes.

17. The probe of claim 7 , wherein probe is integrated into an electron microscope for in-situ optical measurement.

18. The probe of claim 7 , further comprising:

a k-space filter, wherein the k-space filter is inserted into an optical path to remove low-k components; and

an objective lens, the objective lens configured to focus high-k information to form a ring pattern at an image plane, which is sent into a charge-coupled device (CCD) of a spectrometer for analysis.

19. The probe of claim 18 , wherein the probe is used for microscopy using linear wavelengths.