Optical antennas for sub-wavelength localization and giant enhancing light

This paper focuses on an electrochemical etching method for producing sub-wavelength tapered optical antennas to probe intrinsic vibrational modes of a specimen on the nanoscale. A new electrochemical cell and in situ etching current kinetics allow ones to improve the yield of tips with a well-defined geometry up to 95 %. A capability of gold tips to enhance highly focused laser light due to the plasmonic effect is evidenced by near-field Raman spectroscopy and microscopy of a bundle of single-walled carbon nanotubes.