ENHANCED SCATTERING RESPONSE OF PLASMONIC NANO- WIRES SCANNED BY TIGHTLY FOCUSED BEAMS

摘要

Highly sensitive, high speed nanoscale measurement is an important capability for the modern industry. Scattering response enhancement is among the various ways to increase the speed or the sensitivity of a measurement. This work is concerned with the far field response enhancement due to the plasmonic resonance, excited in nanowires by tightly focused beams. Considering nanowires which are significantly smaller than the wavelength, their scattering response shows an appreciable dependence on the position of the nanowire in the tightly focused field. This dependence is numerically investigated for nanowires of 30nm diameter in a 2D geometry. The far field response is evaluated for perfectly conducting nanowires, dielectric (quartz) nanowires and silver nanowires. The results suggest that the scattering response corresponding to the silver nanowires, being in plasmonic resonance can be up to 5 times stronger. This is partly due to the enhancement of longitudinal dipole excitation by the corresponding electric field component. The numerical evaluation demonstrated a position sensitivity of lnm corresponding to a reasonable and conservative value of 33 dB signal to noise ratio.