Liquid crystal clad metamaterial with a tunable negative-zero-positive index of refraction

A near-IR metamaterial having a tunable index of refraction from negative, through zero, to positive values has been proposed. Liquid crystal layers are incorporated both as a superstrate and a substrate onto a conventional NIM. Tuning the permittivity of the liquid crystal layers controls the value of the effective permittivity in an averaging manner. Combined with proper magnetic resonances provided by a pair of silver strips separated by a thin layer of alumina, the effective index of refraction can be reconfigured between negative, zero, and positive values. The ability to vary the permittivity of the liquid crystal layers also provides a method to control the bandwidth of the negative index behavior.