Resonant Optical Antennas

TLDR

Optical antennas bridge propagating radiation and confined optical fields, offering potential for characterization, manipulation, and information processing, though their resonant behavior contradicts classical theory yet aligns with simulations accounting for finite conductivity. We fabricated nanometer‑scale gold dipole antennas resonant at optical frequencies, achieving strong field enhancement that produces white‑light supercontinuum and a resonant length much shorter than half the incident wavelength.

Abstract

We have fabricated nanometer-scale gold dipole antennas designed to be resonant at optical frequencies. On resonance, strong field enhancement in the antenna feed gap leads to white-light supercontinuum generation. The antenna length at resonance is considerably shorter than one-half the wavelength of the incident light. This is in contradiction to classical antenna theory but in qualitative accordance with computer simulations that take into account the finite metallic conductivity at optical frequencies. Because optical antennas link propagating radiation and confined/enhanced optical fields, they should find applications in optical characterization, manipulation of nanostructures, and optical information processing.