Plasmonic near-field focusing with nanotips structure

In this paper, a new kind of symmetrical aluminum (Al) nanotips structure based on localized rather traditional propagating surface plasmon polarizations (SPPs) focusing are designed and fabricated successfully. The simulation results about near-field distribution of electric field and reflectance calculations using finite-difference time-domain (FDTD) simulation theory are exhibited and then the device is fabricated mainly by coating Al films with the thickness of 100 nm on n-type doping silicon (Si), cutting into scale of 15mm×15mm by wafer dicing, electron beam lithography (EBL) exposure and ICP etching. The near-field focusing properties about small spot breaking the diffracting limitation with one order enhancement in the near-tip area of this structure are demonstrated experimentally using scanning nearfield optical microscopy (SNOM), and the comparisons to simulation results are analyzed, so as to reveal a potential application in capturing near-field focusing images quickly by applying exterior voltage signals based on our structure with nanotips.