1. Connection Symposium Toronto, ON May 8, 2009 Meta-Screen for High Resolution Optical Microscopy Yan Wang*, Amr S. Helmy, & George V. Eleftheriades University of Toronto

2. Connection Symposium Toronto2 May 8, 2009 Overview BackgroundBackground –Conventional optical microscope and its resolution limit; –Development in various high resolution microscopy technologies and their pros and cons. Scanning near-field optical microscopy (SNOM)Scanning near-field optical microscopy (SNOM) –Basic operating principles and drawbacks. Theory of meta-screenTheory of meta-screen –Improves the current SNOM resolution; –Design principles and performances; ConclusionConclusion

3. Connection Symposium Background Optical microscopy – seeing things with lightOptical microscopy – seeing things with light –Conventional compound optical microscopes Toronto3 May 8, 2009 An 1879 Carl Zeiss Jena Optical microscope Mirror Stage (with clips) Objective Lens Eyepiece lens Focus Nikon Eclipse 600 transmitted/reflected light microscope

4. Connection Symposium Background (cont’d) Resolution limit of conventional optical microscopesResolution limit of conventional optical microscopes –Abbey’s diffraction limit (200nm for the visible spectrum) Propagating waves: e -jβz x z k0k0 -k 0 kxkx Spectrum of the spatical information Toronto4May 6, 2010 Evanescent waves: e -αz

5. Connection Symposium Toronto5 May 6, 2010 (cont’d) Background (cont’d) Efforts in achieving high-resolution (beyond the diffraction limit)Efforts in achieving high-resolution (beyond the diffraction limit) Electron microscope (TEM, SEM and REM etc.) Atomic force microscope (AFM) Pendry’s “perfect lens” (meta-material application) Jason Palmer, BBC news, Friday, 28 August 2009, “Single molecules stunning image” J.B. Pendry, “Negative refraction makes a perfect lens” Phys. Rev. Lett. 85, 18 (2000).

6. Connection Symposium SNOM Scanning near-field optical microscopeScanning near-field optical microscope Toronto6May 6, 2010 WiTech alpha300S Scanning Near-field Optical Microscope, ϋlm, Germany Human leucocyte SPP propagation Aperture probe limits resolution –Operates in the near-field –Does not depend on the wavelength of the illuminating light –Suffers tremendous power loss

7. Connection Symposium Meta-screen Toronto7 May 6, 2010 Improve the focusing ability of the aperture (multi-aperture approach)Improve the focusing ability of the aperture (multi-aperture approach) –Circular aperture vs. slot aperture –Single-slot vs. multi-slot L. Markley et. al., “A spatially shifted beam approach to subwavelength focusing,” Phys. Rev. Lett. 101, 10 (2008). Bethe’s diffraction theorySlot antenna theory

8. Connection Symposium Meta-screen Multi-slot metallic transmission screen (Meta-Screen)Multi-slot metallic transmission screen (Meta-Screen) Toronto8May 6, 2010 Target Beamwidth FWHM = 0.12λ 0 Transmission screen Weight = 1, -1/2, 1/5, -1/10, … y x z x z

9. Connection Symposium Meta-screen (cont’d) Meta-screen improves near-field focusingMeta-screen improves near-field focusing Material: Ag (ε r = -31.26-j1.14) Thickness = 40nm, Slot width = 40nm Central slot length = 200nm Satellite slot length = 130nm Slot separation distance = /10 = 83nm Toronto9May 6, 2010 Y. Wang et. al., “Plasmonic meta-screen for alleviating the trade-offs in the near-field optics ”, Optics Express, 17, 12351-12361 (2009) Magnitude of Ex (log scale)

10. Connection Symposium Thank you!