Localized surface plasmons in lamellar metallic gratings

Surface electromagnetic modes of lamellar metallic gratings made of gold are analyzed both theoretically and experimentally in the 0.21.0 eV spectral range for p-polarized light. For deep enough grooves, we show how waveguide resonances that show no dispersion with parallel momentum appear in the photonic band structure of these surface plasmons. In these resonances the electric field is highly localized inside the grooves and is almost zero in all other regions. We also illustrate the existence of hybrid modes, combination of standing waves with propagating surface plasmon polaritons. Experimental evidence of the excitation of both kind of localized surface plasmons is given for lamellar gratings of period 3.5 /spl mu/m with grooves 0.5 /spl mu/m wide and 0.6 /spl mu/m deep.

[1]  D. Lynch,et al.  Handbook of Optical Constants of Solids , 1985 .

[2]  T. A. Leskova,et al.  Resonant scattering of electromagnetic waves from a rectangular groove on a perfectly conducting surface , 1997 .

[3]  H. Lezec,et al.  Extraordinary optical transmission through sub-wavelength hole arrays , 1998, Nature.

[4]  J. Pendry,et al.  Collective Theory for Surface Enhanced Raman Scattering. , 1996, Physical review letters.

[5]  Kitson,et al.  Physical origin of photonic energy gaps in the propagation of surface plasmons on gratings. , 1996, Physical review. B, Condensed matter.

[6]  D. Mills,et al.  Interaction of electromagnetic waves with periodic gratings: Enhanced fields and the reflectivity , 1983 .

[7]  H. Raether.  Surface Plasmons on Smooth and Rough Surfaces and on Gratings , 1988 .

[8]  A. Wirgin,et al.  Role of waveguide and surface plasmon resonances in surface-enhanced Raman scattering at coldly evaporated metallic films , 1984 .

[9]  Ping Sheng,et al.  Exact eigenfunctions for square-wave gratings: Application to diffraction and surface-plasmon calculations , 1982 .

[10]  A. Wirgin,et al.  Can surface-enhanced raman scattering be caused by waveguide resonances? , 1984 .

[11]  T. W. Preist,et al.  Standing-wave surface-plasmon resonances with overhanging zero-order metal gratings , 1998 .

[12]  John B. Pendry,et al.  Photonic Band Structures , 1994 .

[13]  F. J. Garcia-Vidal,et al.  SURFACE SHAPE RESONANCES IN LAMELLAR METALLIC GRATINGS , 1998 .

[14]  J. R. Sambles,et al.  Stationary Surface Plasmons on a Zero-Order Metal Grating , 1998 .

[15]  J. Roy Sambles,et al.  Sharp Surface-Plasmon Resonances on Deep Diffraction Gratings , 1997 .