Quantitative spectroscopy on individual wire, slot, bow-tie, rectangular, and square-shaped optical antennas

  • Author: M. Husnik, J. Niegemann, K. Busch, and M. Wegener
  • Source: Opt. Lett. 38, 4597-4600 (2013)
  • Date: 6.11.2013
  • Abstract:

    By using a recently introduced approach combining a focus-modulation technique with a common-path interferometer, we measure quantitatively the extinction, scattering, and absorption cross-section spectra of individual optical antennas. The experimental results on thin-wire antennas, slot antennas, bow-tie antennas, rectangular antennas, and square-shaped antennas resonating at around 1.4 μm wavelength are discussed. We find increased resonant scattering cross sections for the latter four antennas compared to the thin-wire antenna, both in absolute terms and relative to the absorption cross section. The square-shaped antenna’s resonant extinction cross section approaches the limit of a coherent point dipole. However, the ratio of the resonant extinction cross section to the geometrical cross section of 38 is largest for the simple thin-wire antenna.