Polarization conversion through collective surface plasmons in metallic nanorod arrays

Abstract

For two-dimensional (2D) arrays of metallic nanorods arranged perpendicular to a substrate several methods have been proposed to determine the electromagnetic near-field distribution and the surface plasmon resonances, but an analytical approach to explain all optical features on the nanometer length scale has been missing to date. To fill this gap, we demonstrate here that the field distribution in such arrays can be understood on the basis of surface plasmon polaritons (SPPs) that propagate along the nanorods and form standing waves. Notably, SPPs couple laterally through their optical near fields, giving rise to collective surface plasmon (CSP) effects. Using the dispersion relation of such CSPs, we deduce the condition of standing-wave formation, which enables us to successfully predict several features, such as eigenmodes and resonances. As one such property and potential application, we show both theoretically and in an experiment that CSP propagation allows for polarization conversion and optical filtering in 2D nanorod arrays. Hence, these arrays are promising candidates for manipulating the light polarization on the nanometer length scale.

Circularly and elliptically polarized near-field radiation from nanoscale subwavelength apertures

“…It has been recently demonstrated that the polarization of diffraction limited incident beams can be manipulated using nanoparticle based antenna geometries [12][13][14][15] and nanorod arrays. 16 Elliptically and circularly polarized near-field radiation can also be achieved through subwavelength apertures by utilizing a circular hole surrounded by elliptical gratings 17 and L-shaped hole arrays. 18 In this study, two alternative techniques are investigated to obtain circularly and elliptically polarized near-field radiation from subwavelength apertures.…”

Optical and electrical properties of gold nanowires synthesized by electrochemical deposition

“…32 Previous studies have demonstrated that, in an array of nanorods, the SPR of the individual nanorods can be viewed as harmonic oscillators that couple to each other, leading to a resonance shift as well as a changed near-field distribution. 33 In the present work, the mean distances between the wire surfaces facing each other decreases from 470 to 370 nm with the nanowires diameters increasing from 30 to 130 nm at the certain area density of 1 Â 10 8 wires/cm 2 (with the assumption of all nanopores in the templates being filled). 34 It is reported that if the distance of the nanowires or nanorods surfaces is around or smaller than 2.5 times the diameter, the coupling among the nanowires or nanorods results in a red shift of the transverse plasmon.…”

“…The blue-shift of the SPR peak with increasing incident angle is mainly caused by the phase delay of the incident light due to the array. 33 It is known that the strongest coupling occurs when the linked electric fields are in phase. With increasing angle a, the coupling-effect between the neighboring wires is expected to decrease because of the increasing phase difference of incident electric field.…”

Characterization of guiding properties of metallic nanorod metamaterials

“…The spectral sensitivity under different excitation conditions is shown to investigate the localized surface plasmon in metallic nanorod arrays. The results of our simulation are compared with other presented work 8 . In addition, to observe the characteristics of plasmonic waveguides, the incident light were changed to show the variation of electric field distribution and energy flow.…”