Very thin layers of patterned metamaterials can be used to create unique low-profile, flat, optical devices, such as lenses, filters and other optical components. Metamaterials can achieve a large range of effective index-of-refraction values, enabling a new realm of diffractive and gradient index optical devices. To produce metamaterial optics or metasurfaces, the shape and size of each metamaterial element is controlled, allowing nearly arbitrary distributions of refractive index and other optical properties to be controlled with tremendous precision. As an example, we have applied the metamaterial approach to demonstrate the design and fabrication of a dual-polarization hologram—a device that produces two different images when illuminated by two different polarizations. Holographic metamaterials have particular relevance for infrared optical components, where traditional materials have many more limitations.
More details about the dual-polarization hologram can be found in the article by Y.-J. Tsai et al., "Arbitrary birefringent metamaterials for holographic optics at λ = 1.55 μm" published in Optics Express, Vol. 21, pp. 26620-26630 (2013).