Characterization of Sierpinski carpet optical antenna at visible and near-infrared wavelengths

We present fabrication, characterization, and simulation results on an optical antenna inspired by the Sierpinski carpet fractal geometry for operation in the visible and near-infrared wavelength regions. Measurements and simulations of the far-field scattering efficiency indicate a broadband optical response. Two-photon photoluminescence images provide maps of the near-field intensity distribution, from which we extract an enhancement factor of similar to 70. To explore the effect of morphology on the optical response of a large assembly of particles, we also present results on an arbitrarily chosen pseudo-random configuration as well as a periodic array.