Locally Enhanced and Tunable Optical Chirality in Helical Metamaterials
  We report on a numerical study of optical chirality. Intertwined gold helices illuminated with plane waves concentrate right and left circularly polarized electromagnetic field energy to sub-wavelength regions. These spots of enhanced chirality can be smoothly shifted in position and magnitude by varying illumination parameters, allowing for the control of light-matter interactions on a nanometer scale. 
Philipp Gutsche, Raquel M\"ausle, Sven Burger
physics.optics