Beam manipulation via plasmonic structure

1. Beam manipulation via plasmonicstructure KwangHee, Lee 2010. 5. 19 Photonic Systems Laboratory

2. Contents • Introduction of surface plasmonpolariton(SPP) • Extraordinary transmission(EOT) • Effect factors of transmission • Exit patterning • Summary

3. Dielectric x - - - - + + + + + + + + Metal What is the SPP? z Evanescent modes for

4. SPP at a single interface

5. Where can SPP be used? Integrated electro-photonics, will remove the crosstalk and Ohmic loss of Electronics meanwhile retaining the nano-features of Electronics

6. EOT • Extraordinary Transmission (EOT) Sub-wavelength hole arrays : peak at above a0 contribution of surface modes Due to grating coupling at regular, periodic lattice Phase matching condition Ebbesen, T. W., Lezec, H. J, Ghaemi, H. F., Thio, T., and Wolff, P. A. “Extraordinary optical transmission through sub-wavelength hole arrays.” Nature, 931:667–669. 1998.

7. EOT • Extraordinary Transmission (EOT) EOT occurs at another structures : Bull’s eye, square dimple array, slit array Thio, Tineke, Pellerin, K. M., Linke, R. A., Lezec, H. J., and Ebbesen, T. W. “Enhanced light transmission through a single subwavelength aperture.” Opt. Lett., 26(24):1972–1974. 2001. Porto, J. A., Garcia-Vidal, F. J., and Pendry, J. B. “Transmission resonances on metallic gratings with very narrow slits.” Phys. Rev. Lett., 83(14):2845–2848. 1999.

8. Effect factors of transmission • Factor for Surface Plasmon Polaritons (SPP) • Flim thickness : T saturation for small thickness (order of skin depth) • Hole width : T increases and the peaks broaden for increasing hole width Degiron, A., Lezec, H. J., Barnes,W. L., and Ebbesen, T.W. “Effects of hole depth on enhanced light transmission through subwavelength hole arrays.” Appl. Phys. Lett., 81(23):4327–4329. 2002. van derMolen, K. L., Segerink, F. B., van Hulst, N. F., and Kuipers, L. “Influence of hole size on the extraordinary transmission through subwavelength hole arrays.” Appl. Phys. Lett., 85(19):4316–4318. 2004.

9. Effect factors of transmission • Factor for Surface Plasmon Polaritons (SPP) • Coupled cavity modes in the grooves • h : about frequency • d : about in-phase re-emmision • Exit side grooves don’t influence T García-Vidal, F. J., Lezec, H. J., Ebbesen, T. W., and Martín-Moreno, L. “Multiple paths to enhance optical transmission through a single subwavelength slit.” Phys. Rev. Lett., 90(21):213901. 2003.

10. Effect factors of transmission • Localized Surface Plasmons (LSP) In contrast to PEC case, the maximum in the transmission of real metal near 580 nm can be associated with the excitation of a localized surface plasmon. the nanohole excitation decays not only into scattered light, but into surface plasmon polaritons. Chang et al.,“Surface plasmon generation and light transmission by isolated nanoholes and arrays of nanoholes in thin metal films”, Opt. Express, Vol.13, No.8, 3150, 2005.

11. Effect factors of transmission • Localized Surface Plasmons (LSP) Charges accumulate at the edges with a length scale of one wavelength. This increasing charge density enhances the electric field. The electric field is proportional to the charging time or equivalently 1/f. Seo et al.,“Terahertz field enhancement by a metallic nano slit operating beyond the skin-depth limit”, Nature Photonics, Vol.3,No.3,152-156, 2009.

12. Effect factors of transmission • Waveguide resonance Normalized-to-area transmittance at resonance is proportional to the aspect ratio, and to the dielectric constant inside the hole. A transmission peak develops at approximately λc=2ay, with increasing maximum transmittance and decreasing linewidth as ay/ax increases. F.J.Garcia-Vidal et al., “Transmission of Light through a Single Rectangular Hole” , PRL, 95, 103901, 2005.

13. Exit surface patterning • Exit surface patterning enables directional emission Lezec, H. J., Degiron, A., Devaux, E., Linke, R. A., Martin-Moreno, L., Garcia-Vidal, F. J, and Ebbesen, T. W. “Beaming light from a subwavelength aperture.” Science, 297:820– 822. 2002.

14. Exit surface patterning • Narrow beam profile is obtained with about 10 grooves Martín-Moreno, L., Garcia-Vidal, F. J., Lezec, H. J., Degiron, A., and Ebbesen, T. W. “Theory of highly directional emission from a single subwavelength aperture surrounded by surface corrugations.”Phys. Rev. Lett., 90(16):167401. 2003.

15. Exit surface patterning • Off-axis beaming with asymmetric surface gratings Seyoon Kim, Hwi Kim, Yongjun Lim, and ByounghoLee, “Off-axis directional beaming of optical field diffracted by a single subwavelength metal slit with asymmetric dielectric surface gratings”Applied Physics Letters 90, 051113, 2007

16. Applications • Near-field optical probe(conical geometry) • Micro-fluidic detector ε=1.8978 ε=2.2506 Drezet et al., “Extension of Bethe’s diffraction model to conical geometry” ,Europhys. Lett., 54(6), pp. 736-740, 2001. Bravo-Abad et al., “Transmission properties of a single metallic slit” ,Physical Review E, 69, 026601, 2004.

17. Applications • Optical switching using nonlinear material d=0.75, a=0.05, h=0.45 um The transmission spectra differ for increasing and decreasing fluxes.  Optical bistability Porto et al., “Optical bistability in subwavelength slit apertures containing nonlinear media”, Phys. Rev. B, 70, 081402, 2004.

18. Summary • SPP has a great possibility to integrate electronics and photonics • Extraordinary transmission is generated from SPP which is influenced by geometrical parameters. • Transmission is also influenced by LSP and waveguide resonance. • With exit surface patterning, directional emmision and off-axis beaming can be possible. • EOT is applicable to various optical devices such as switch, probe and so on.