Waveplates are planar devices used in optics and optoelectronics to change the polarization state of light. made of anisotropic dielectric materials such as crystals and thin films, waveplates are not known to exhibit achromatic performance over the visible regime. Inspired by the microvillar structure of R8 cells functioning as polarization converters in the eyes of stomatopod crustaceans, we conceived, designed, fabricated and tested periodically multilayered structures comprising two different types of arrays of nanorods. morphologically analogous to the ocular cells, here we show that the periodically multilayered structures can function as achromatic waveplates over the visible regime.

A thin film comprising parallel tilted nanorods was deposited by directing silver vapor obliquely towards a plane substrate. The reflection and transmission coefficients of the thin film were measured at three wavelengths in the visible regime for normal-illumination conditions, using ellipsometry and walk-off interferometry. The thin film was found to display a negative real refractive index. Since vapor deposition is a well-established industrial technique to deposit thin films, this finding is promising for large-scale production of negatively refracting metamaterials.

A normalized admittance diagram assists in describing and designing multilayered structures to excite long-range surface-plasmon-polariton (LRSPP) waves of either the p- or the s-polarization state. These structures comprise symmetric periodic multilayers on one or both sides of a metal thin film in either the Kretschmann or the Sarid configuration. The normalized admittance diagram even assists in designing structures that can be used to excite LRSPP waves of both polarization states simultaneously.

Sandwich films comprising arrays of silver/silicon-dioxide/silver nanosandwiches were grown by the oblique angle deposition technique. For normally incident light, these films present a negative-real refractive index (NRRI) over almost the entire visible regime, with quite high transparency and figures of merit, regardless of the orientation of the incident electric field. A broad distribution of nanosandwich sizes is responsible for the breadth of the NRRI spectral regime.

Refraction of light from an isotropic dielectric medium to an anisotropic dielectric material is a complicated phenomenon that can have several different characteristics not usually discussed in electromagnetics textbooks for undergraduate students. With a simple problem wherein the refracting material is uniaxial with its optic axis normal to the interface plane, the phenomena of (i) negative/positive refraction, (ii) negative/positive phase velocity, (iii) counterposition of the phase velocity and the time-averaged Poynting vector, and (iv) 'negative refraction' of the energy flux density can be examined. The last-named phenomenon is really negative deflection by refraction.