Optical transmissivity of single metallic V-grooves

The authors present an experimental study of the spectral properties of metallic single V-grooves. The V-groove structures are fabricated by a focused ion beam technique. They are milled in a 500 nm gold layer deposited on a 0.5 mm quartz substrate. The entrance widths (w) of the V-grooves vary between 100 and 200 nm, exit gaps (g) are in the range of 15-22 nm, and the opening angles (α) are 9-22 degree. Optical transmission through V-grooves is governed by two major effects: direct tunneling due to waveguide (photonic) mode and the excitation of the superfocusing surface plasmon polariton (SPP) mode in the V-groove.