Causality relations for materials with strong artificial optical   chirality
  We demonstrate that the fundamental causality principle being applied to strongly chiral artificial materials yields the generalized Kramers-Kronig relations for the observables -- circular dichroism and optical activity. The relations include the Blaschke terms determined by material-specific features - the zeros of transmission amplitude on the complex frequency plane. By the example of subwavelength arrays of chiral holes in silver films we show that the causality relations can be used not only for a precise verification of experimental data but also for resolving the positions of material anomalies and resonances and quantifying the degree of their chiral splitting. 
M.V. Gorkunov, V.E. Dmitrienko, A.A. Ezhov, V.V. Artemov, and O.Y.   Rogov
physics.optics