Circular dichroism in single-layered gold sawtooth gratings

We report on the fabrication of single-layered gold sawtooth gratings consisting of sic, V, and N basic units by using an e-beam direct write technique together with a lift-off process. The sic- and N-type sawtooth gratings are 2D chiral but not the V-type sawtooth grating. Large circular dichroism (CD) in the visible range is observed for the chiral sawtooth gratings while there is none for the V-type sawtooth grating. The experimental results are modelled qualitatively by simulations using a finite integration technique. The simulations show that the CD observed is due to the difference in the absorption in the metal for circularly polarized incidence light of different handedness. The sawtooth gratings are simple and can be easily mass produced for possible applications in waveplates and circular polarizers. (C) 2012 Optical Society of America