title: Spatial dispersion and energy in strong chiral medium.
abstract: Since the discovery of backward-wave materials, people have tried to realize a strong chiral medium, which is traditionally thought impossible mainly for the reason of energy and spatial dispersion.We compare the two most popular descriptions of a chiral medium. After analyzing several possible reasons for the traditional restriction, we show that a strong chirality parameter leads to positive energy without any frequency-band limitation in the weak spatial dispersion. Moreover, strong chirality does not result in a strong spatial dispersion, which occurs only around the traditional limit point. For strong spatial dispersion where higher-order terms of spatial dispersion need to be considered, the energy conservation is also valid. Finally, we show that realization of strong chirality requires the conjugated type of spatial dispersion.
authors.affiliation: Center for Computational Electromagnetics and the State Key Laboratory of Millimeter Waves, Department of Radio Engineering, Southeast University, Nanjing 210096, P. R. China. czhang@unm.edu
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.forename: Tie Jun
authors.initials: TJ
authors.lastname: Cui