New Material for Advanced MetamaterialsCategory: Science & Technology
Posted: May 15, 2012 06:00PM
Metamaterials are a curious class of materials with highly engineered structures, so as to have unusual characteristics. In the case of optical metamaterials, light can be made to bend backwards, which opens the door to invisibility cloaks and super lenses. Making metamaterials is not easy though, not only because of their intricate structures but also because of the materials they are made of. Currently the best metals to use are silver and gold, which are both expensive and neither plays well semiconductors. Fortunately researchers at Purdue University have discovered a new metamaterial that uses different compounds, and has a few new tricks.
Instead of the traditional precious metals, the researchers used aluminum-doped zinc oxide (AZO) and zinc oxide to construct the new metamaterial. With 16 alternating layers of AZO and zinc oxide, the metamaterial creates an extreme anisotropy for the light that passes through. This causes the light to dispersion to be in a hyperbolic pattern, which greatly changes the light's behavior.
Along with being cheaper than silver or gold, this new design offers something current metamaterials cannot; control after creation. The properties of the metamaterial can be altered by either varying the aluminum in the AZO while the material is being made, or by applying an electric field to the finished device. With an external electric field, the optical properties of the metamaterial can be tuned or even switched. Being able to shift the frequencies of light the metamaterial interacts with could greatly impact how it can be used and open up new realms of possibilities.