J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 1 NANOTECHNOLOGY Part 3. Optics Micro-optics Near-Field Optics Scanning Near-Field Optical Microscopy Surface Plasmons

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 2 Micro-Optics

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 3 Far-Field vs. Near-Field Helmholtz eq. => propagating: evanescent:

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 4 The Dipole Field dl is the length of the current element,  is short for (2  f/ )-  t w signal frequency, t is the time (=1/f), c is the speed of light Z 0 free space impedance, I is the current in the element  is the zenith angle to radial distance r, wavelength of the signal r distance from the element to point of observation hyperphysics.phy-astr.gsu.edu/

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 5 Near-Field Theory We have to solve the full set of Maxwell's equations. Brute force limits applicability due to computing time restrictions. Complex geometries call for discretization in direct space. Green's Dyadic Technique, Discrete Dipole Approximation Finite Difference Time Domain Problems combining µm-scale structures (e.g., substrates, waveguides) and nm-structures including measurement process

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 6 Scanning Near-Field Optical Microscope (1) tnweb.tn.utwente.nl 'scatterer' 'aperture'

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 7 SNOM (2) Operation modes of scatter-type SNOM's E2E2 Photon Scanning Tunneling Microscope (PSTM)

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 8 SNOM (3) Scatter-type near-field microscopy: Tip enhancement =>Tip enhanced Raman and fluorescence spectroscopy Left: Near-field Raman image at 2615 cm -1 (exc. 633 nm) of SWNT's acquired with a silver tip; Right: topography Distance dependence of Raman signal A.Hartschuh et al., PRL. 90, (2003) 1 µm

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 9 SNOM (4) illumination in total internal reflection Operation modes of aperture-type SNOM's M.A.Paesler, P.J.Moyer, Near-Field Optics, Wiley, New York, 1996

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 10 SNOM (5) 100x100x50 nm Au Experimental SNOM images, polarization directions along (a) x and (b) y, (c), (d) corresponding LDOS calculations C.Chicanne et al., PRL 88, (2002)

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 11 SNOM (6) Single molecule detection courtesy N. van Hulst, Univ. Twente Near-field lithography UV mediated crosslinking in PPV courtesy of R.Riehn, Univ. Cambridge pol.

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 12 Dielectric Nanoparticles J.C.Weeber et al., Phys.Rev.Lett. 77, 5332 (1996) PSTM images of glass nanopads TM TE Topography

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 13 Metal Nanoparticles (1) The British Museum

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 14 Metal Nanoparticles (2) J.R.Krenn et al., Phys.Rev.Lett. 82, 2590 (1999) AFMPSTMTHEORIE 500 nm

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 15 Subwavelength Optical Elements (1) LIGHT SOURCES zinc oxide 100 nm wire laser Michael H. Huang et al., Science 292, 1897 (2001) DETECTORSAPERTURES optical near-field of VCSEL courtesy O.Marti, Univ.Ulm 15 µm T.Thio et al., Physica B 279, 90 (2000) Swiss Federal Institute of Technology at Lausanne quantum dots biomolecular det.

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 16 Subwavelength Optical Elements (2) WAVEGUIDES TiO 2 (R.Quidant, Univ.Dijon)Gold (Univ.Graz) PHOTONIC CRYSTALS iapnt.iap.uni-jena.de

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 17 Surface Plasmons (1) +1 or 2 - dimensional +"non diffraction limited" +near – field enhancement +spectral selectivity +temporal dynamics ~ 10 fs – high damping – interfacing

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 18 Surface Plasmons (2) (Bio)molecule detection Spreeta, Texas Instruments

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 19 Surface Plasmons (3) Enhanced optical transmission E. Altewischer et al., Nature 418, 304 (2002) originally revealed by T.Ebbessen et al., ISIS, Strasbourg PSTM of locally excited surface plasmons P.Dawson et al., Phys.Rev.Lett. 72, 2927 (1994)

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 20 Fluorescence Imaging of SP's Ditlbacher et al., APL 80, 404 (2002); APL 84, 1762 (2002) Rhodamin 6G  max = 530 nm,  max = 570 nm 'DiR'  max = 750 nm,  max = 790 nm 20 µm 10 µm

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 21 SP Mirror & Beamsplitter SP Bragg Mirror SP Beamsplitter 10 µm 20 µm

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 22 SP Interferometer 10 µm H.Ditlbacher et al., APL 84, 1762 (2002) Featured in The Economist 43/2002

J.R.Krenn – Nanotechnology – CERN 2003 – Part 3 page 23 (Some kind of) Conclusion M.A.Paesler, P.J.Moyer, Near-Field Optics, Wiley, New York, 1996 [1] = D.W.Pohl, in Advances in Optical and Electron Microscopy, eds. C.J.R.Sheppard and T.Mulvey, Academic Press, London 1991