Nano Optics: Overview of Research Activities. Sergey I. Bozhevolnyi SENSE, University of Southern Denmark, Odense, DENMARK

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1 Nano Optics: Overview of Research Activities SENSE, University of Southern Denmark, Odense, DENMARK Optical characterization techniques: Leakage Radiation Microscopy Scanning Near-Field Optical Microscopy Raman microscopy Dielectric-loaded SPP waveguides Design considerations Propagation, bending and splitting Wavelength-selective components

2 Optical characterization techniques: Imaging of SP in-plane propagation Ilya P. Radko Near-field imaging (SNOM) of waveguides Tobias H. Jensen Valentyn S. Volkov Jacek Gosciniak Nonlinear & Raman high-resolution spectroscopy Sergey M. Novikov Jonas Beermann

3 Three possible configurations Kretschmann SPP excitation (thin metal film) SPP excitation through nano-slit (opaque metal film) SPP excitation on surface defects (thin metal film) Near-field detection of SPP fields Near-field detection of SPP fields Mapping of SPP fields by detection of leakage radiation

4 Kretschmann SPP excitation Near-field imaging of dielectric-loaded SPPs 26x80 μm 26x80 μm C. Reinhardt et al., Opt. Lett. 31, 1307 (2006). Topography Near-field image λ 0 =1520nm

5 SPP excitation through nano-slit Near-field imaging of nano-slit couplers and focusers λ 0 = 1520nm, 70x26μm 10 µm R=30 µm F. López-Tejeira et al., Nature Physics 3, 324 (2007). λ 0 = 1520nm, 64x32μm

6 SPP excitation on surface defects Mapping of SPP fields through leakage radiation k 0 k spp k spp Air Au 15 μm SiO 2 k LR θ LR θ LR k 0 n k LR = k 0 n 10 μm 2 μm Opt. Express 15, 6576 (2007), Opt. Express 16, 3924 (2008).

7 Fiber excitation of waveguides + SNOM IR vidicon Mirror Detector Optical fiber Microscope objective SNOM head OSA Sample Radiation from tunable laser nm) 1620 (1430 SNOM fiber tip: X,Y stage X,Y,Z stage 500 nm

8 SNOM images PhC waveguides: Plasmonic waveguides: 2 μm

9 Nonlinear Scanning Optical Microscopy Experimental setup: (FH) (+TPL) MANY different applications: E.g. local detection of molecular orientations, variations/defects. 80MHz, 100fs λ ~ nm Samples: holes, nanoparticles, fibers, waveguides, crystals, fractals. TPL resolution better than 0.6 μm High resolution information about local nonlinearities and field enhancements in nanostructures, also in-depth e.g. liquids. We can evaluate the field enhancement in nanostructures: 2 μm χ = TPL TPL bump film P P film bump 2 2 A A film bump Typical μm 2 images obtained in 15min. We have previously made near-field investigations (TPL-SNOM) of e.g. organic nanofibers. Because of our movement the detection system still needs to be arranged. With TPL-SNOM we have topographic information and resolution is around 300nm.

10 Confocal Raman scanning microscopy We have a commercial setup (Alpha300A) for confocal Raman scanning microscopy with integrated AFM from Witec: This setup was installed 18-20th June (2008) Optical resolution ~ 0.2 μm, vertical ~0.5 μm. Spectral resolution ~0.02 wavenumbers AFM with integrated active vibration isolation table We have practiced with cancer cells Our excitation λ=532nm Spectra from single point (100ms) Microscope stage resolution 4nm lateral, 0.5nm vertical

11 Surface-enhanced Raman imaging dx x dy 169x511 [nm] array period: Lx x Ly 908x893 [nm] black red green Size 8 3 µm 2100 Rhodamine 6G arb. unit cm -1

12 Dielectric-loaded SP channel waveguides (DLSPPWs) k sp = ω c ε ε m m εd + ε d ω/ω p 0,8 ω sp light in air SP in air light in dielectric SP waves in dielectric 0,6 0,4 0,2 dielectric metal 0,0 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 It is very important to use as thick as possible (within single-mode guiding regime) stripes in order to achieve a large-refractive index contrast! k/k 0

13 DLSPPWs: PLASMOCOM It is very important to use as thick as possible (within single-mode guiding regime) stripes in order to achieve a large-refractive index contrast and, thereby, strong lateral confinement of the DLSPPW mode! w = t = 600 nm, λ = 1.55 μm N ef = 1.29; L = 44.4 μm Phys. Rev. B 75, (2007).

14 DLSPPWs: PLASMOCOM UV lithography: targeting t 600 nm, w 600 nm (for λ ~ 1.5 μm) Direct coupling to the polymer/gold interface Appl. Phys. Lett. 92, (2008).

15 DLSPPWs: PLASMOCOM Direct coupling to the polymer/gold interface (80-µm-long DLSPPWs): Phys. Rev. B 78, (2008). DLSPPW mode width ~ 800 nm DLSPP propagation length ~ 50 µm

16 DLSPPWs: PLASMOCOM Opt. Express 16, (2008).

17 DLSPPWs: PLASMOCOM Opt. Express 16, (2008).

18 DLSPPWs: PLASMOCOM Appl. Phys. Lett. 94, (2009). Opt. Lett. 34, 310 (2009).