Dielectric nano-antennas are promising elements in nanophotonics due to their low material loss and strong leaky-mode optical resonances. In particular, light scattering can be easily manipulated using dielectric nano-antennas. To take full advantage of dielectric nano-antennas and explore their new optical applications, it is necessary to fabricate three-dimensional nano-structures under arbitrary conditions such as in non-planar substrates. Here, we demonstrate full-visible-range resonant light scattering from a single dielectric optical nano-rod antenna. The nano-rod antenna was formed by electron beam-induced deposition (EBID), a promising three-dimensional nanofabrication technique with a high spatial resolution. The nano-rods consist of amorphous alloys of C and O, with a width of 180 nm on average and a length of 4.5 μm. Polarization-resolved dark-field scattering measurements show that both transverse-electric and transverse-magnetic mode resonances cover the full visible range as the height of the nano-rod antenna varies from 90 to 280 nm. Numerical simulations successfully reproduce the measured scattering features and characterize the modal properties, using the critical points dispersive dielectric constant of the EBID carbonaceous material. Our deep understanding of resonant light scattering in the EBID dielectric nano-antenna will be useful for near-field measurement or for the implementation of three-dimensional nanophotonic devices.
Bibliographical noteFunding Information:
M.-K.S. acknowledges support for this work by the National Research Foundation of Korea (NRF) (2013R1A2A2A01014224, 2014M3C1A3052537 and 2014M3A6B3063709). H.-G.P. acknowledges support by the NRF grant funded by the Korean government (MSIP) (No. 2009-0081565). The authors thank Dr. Ho-Seok Ee for the helpful discussions.
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