Metallic nano-optic lenses and beam shaping devices

• US 20050161589A1
• Filed: 12/02/2004
• Published: 07/28/2005
• Est. Priority Date: 12/05/2003
• Status: Active Grant

• Current Assignee: University Of Pittsburgh (University of Pittsburgh of The Commonwealth System of Higher Education)
• Original Assignee: University Of Pittsburgh (University of Pittsburgh of The Commonwealth System of Higher Education)
• Inventors: Capelli, Christopher C., Sun, Zhijun, Kim, Hong Koo
• Granted Patent: US 7,315,426 B2
• Time in Patent Office: Days
• US Class Current: 250/216
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 5/008 Surface plasmon devices diffractive gratings with a pitch less than or comparable to the wavelength G02B5/1809; surface plasmons in integrated optics G02B6/1226; optical analysis of materials by means of surface plasmons G01N21/553
• CPC Class Codes: G02B 6/1226 involving surface plasmon interaction

Abstract

A nano-optic device comprises a plurality of subwavelength apertures in a metal film or between metal islands. The device is adapted to shape a radiation beam transmitted there through. For example, beam shaping includes at least one of beam focusing, beam bending and beam collimating.

Claims

1. A nano-optic device comprising a plurality of subwavelength apertures in a metal film or between metal islands, wherein the device is adapted to shape a radiation beam transmitted there through.

2. The device of claim 1, wherein shaping the radiation beam comprises at least one of beam focusing, beam bending and beam collimating.

3. The device of claim 1, wherein the device comprises a lens which is adapted to focus the radiation beam to a spot that is the same as or smaller than a peak wavelength of the radiation beam.

4. The device of claim 3, wherein the spot size ranges from 10 nm to 800 nm.

5. The device of claim 3, wherein the lens comprises a metal film having a convex profile such that the apertures have a different depth in a half elliptical profile.

6. The device of claim 3, wherein the lens comprises a flat metal film containing the apertures and a dielectric lens mounted thereon.

7. The device of claim 1, wherein the device is a beam bending device comprising a metal film containing different transparent refractive index materials in different apertures, above different apertures or in and above different apertures.

8. The device of claim 3, wherein the device is a beam bending device comprising a metal film containing, or metal islands separated by, apertures of different width.

9. The device of claim 1, wherein:

the device comprises a metal film or a plurality of metal islands, having a plurality of apertures, each aperture having a width that is less than a first peak wavelength of incident radiation to be provided onto the film or islands; and

the metal film or islands are configured such that the incident radiation is resonant with at least one plasmon mode on the metal film or metal islands, thereby enhancing transmission of radiation having at least one second peak wavelength through the apertures.

10. The device of claim 1, wherein the device further comprises at least one of a spatial, wavelength and polarization filter.

11. The device of claim 1, wherein the device is used together with at least one of a spatial, wavelength and polarization filter.

12. The device of claim 1, wherein each aperture serves as a dipole source radiating optical power at an exit surface of the metal film or islands.

13. The device of claim 12, wherein the dipole elements are designed to have a predetermined phase relationship among them controlled by at least one of a path length difference and an effective index difference in the aperture regions.

14. The device of claim 1, wherein the aperture width is between 15 nm and 700 nm.

15. A nano-optic lens which is adapted to focus an incoming radiation beam to a spot size that is the same as or smaller than a first peak wavelength of the incoming radiation beam.

16. The lens of claim 15, wherein a beam transmitted through the lens is free from a diffraction edge effect.

17. The lens of claim 15, wherein:

the lens comprises a metal film or a plurality of metal islands, having a plurality of apertures, each aperture having a width that is less than the first peak wavelength of incident radiation to be provided onto the film or islands; and

the metal film or islands are configured such that the incident radiation is resonant with at least one plasmon mode on the metal film or metal islands, thereby enhancing and focusing transmission of radiation having at least one second peak wavelength through the apertures.

18. The lens of claim 17, wherein the apertures have different depths and each aperture serves as a dipole source radiating optical power at an exit surface of the metal film or islands.

19. The lens of claim 17, wherein the spot size ranges from 10 nm to 800 Mn.

20. The lens of claim 17, wherein the lens comprises a metal film having a convex profile such that the apertures have a different depth in a half elliptical profile.

21. The lens of claim 17, wherein the lens comprises a flat metal film containing the apertures and a dielectric lens mounted thereon.

22. A method of shaping a radiation beam, comprising passing an incident radiation beam through a device that comprises a metal film or a plurality of metal islands having a plurality of apertures, each aperture having a width that is less than a first peak wavelength of the incident radiation, to shape the beam,

wherein the metal film or islands are configured such that the incident radiation beam is resonant with at least one plasmon mode on the metal film or metal islands, thereby enhancing and shaping transmission of radiation having at least one second peak wavelength through the apertures.

23. The method of claim 22, wherein shaping the beam, comprises at least one of beam focusing, beam bending and beam collimating at least one of a UV, visible and IR radiation beam.

24. The method of claim 23, further comprising performing at least one of wavelength, spatial and polarization filtering of the incident beam in the device.

25. The method of claim 24, wherein each aperture serves as a dipole source radiating optical power at the exit surface of the metal film or islands.

26. A method of focusing a radiation beam, comprising passing the radiation beam through a lens comprised of a metal film or a plurality of metal islands having a plurality of apertures, each aperture having a width that is less than a peak wavelength of the incident radiation, such that the beam is focused to a spot size that is the same as or smaller than the peak wavelength of the radiation beam.

27. The method of claim 26, wherein each aperture serves as a dipole source that radiates optical power at the exit surface of the metal film or islands.

28. The method of claim 27, wherein the dipole elements radiate optical power uniformly all around the radial directions and generate propagating waves that reach a focal point with a predetermined phase retardation, thus contributing to image formation at a focus.

29. The method of claim 27, wherein the spot size ranges from 10 nm to 800 nm.

30. The method of claim 26, wherein the focused beam transmitted through the lens is free from a diffraction edge effect.

31. The method of claim 26, wherein the lens comprises a metal film having a convex profile such that the apertures have a different depth in a half elliptical profile.

32. The method of claim 26, wherein the lens comprises a flat metal film containing the apertures and a dielectric lens mounted thereon.

33. A method of making a device, comprising:

forming a photoresist layer over a device layer;

exposing the photoresist layer by passing incident radiation through a lens that comprises a metal film or a plurality of metal islands having a plurality of apertures, each aperture having a width that is less than a peak wavelength of the incident radiation, such that the beam is focused to a spot size on the photoresist layer that is the same as or smaller than the peak wavelength of the radiation beam;

patterning the exposed photoresist layer; and

etching the device layer using the patterned photoresist layer.

34. The method of claim 33, wherein the device comprises a semiconductor device.