Plasmonic channel waveguides in random arrays of metallic nanoparticles.

Eduardo Pisano,Victor Coello,Cesar E Garcia-Ortiz,Jonas Beermann,Yiting Chen,Sergey I Bozhevolnyi

doi:10.1364/oe.24.017080

Abstract

We report detailed characterization of surface plasmon-polariton guiding along 1-, 1.5- and 2-μm-wide channels in high-density (~75 μm-2) random arrays of gold 70-nm-high and 50-nm-wide nanoparticles fabricated on a 70-nm-thin gold film supported by a 170-μm-thick silica substrate. The mode propagation losses, effective index dispersion, and scattering parameters are characterized using leakage-radiation microscopy, in direct and Fourier planes, in the wavelength range of 740-840 nm. It is found that the mode supported by 2-μm-wide channels propagates over > 10 μm in straight waveguides, with the corresponding S-bends and Y-splitters functioning reasonably well. The results show that the SPP waves can efficiently be guided by narrow scattering-free channels cut through randomly corrugated surface regions. The potential of this waveguiding mechanism is yet to be fully explored by tuning the scattering mean-free path and localization length via the density and size of random nanoparticles. Nevertheless, the results obtained are encouraging and promising diverse applications of these waveguide components in plasmonic circuitry.

Highlights

Plasmonic nanostructures have the potential to combine the very large bandwidth of photonics and the subwavelength confinement of surface plasmon polaritons (SPPs) [1]
We report detailed characterization of surface plasmon-polariton guiding along 1, 1.5- and 2-μm-wide channels in high-density (~75 μm−2) random arrays of gold 70-nm-high and 50-nm-wide nanoparticles fabricated on a 70-nm-thin gold film supported by a 170-μmthick silica substrate
It is found that the mode supported by 2-μm-wide channels propagates over > 10 μm in straight waveguides, with the corresponding S-bends and Y-splitters functioning reasonably well

Summary

Introduction

Plasmonic nanostructures have the potential to combine the very large bandwidth of photonics and the subwavelength confinement of surface plasmon polaritons (SPPs) [1] This could lead to a new generation of nanoscale optical integrated circuits. The effect is similar to that of the photonic band gap in periodically located scatterers [18] and has been characterized by using near-field imaging with a scanning near field optical microscopy and an arrangement for SPP excitation in the Kretschmann configuration with a (practically) plane-wave incidence [16, 17], i.e., with a global (rather than local) SPP excitation This experimental configuration is clearly of limited use, since guided SPP modes overlap spatially with locally excited ones (in the waveguide channels) so that even basic mode characteristics, such as the mode propagation length, become cumbersome to evaluate

Methods

Results

Conclusion