An important and useful property for many optical systems is linearity. Essentially it is why light passing through glass is the same when it exits as when it enters the material. Nonlinear materials however can change light waves, and researchers at the University of Texas at Austin have recently developed a nonlinear meta-mirror that doubles the frequency of the light it reflects.
Nonlinear materials are rare in Nature and are generally not too efficient, requiring high intensities and great distances for the light to propagate through. Metamaterials however are completely unnatural as their optical and electrical properties have been tuned to something that would normally be impossible. Using metamaterials though, the researchers were able to build a device just 400 nanometers thick that would bump the wavelength of light from 8 micrometers up to 4 micrometers; doubling the frequency. Unlike natural nonlinear materials, this device is able to convert light with intensities near that of laser pointers.
The creation of such an efficient and small nonlinear optical system could have many impacts on future optical systems, such as miniaturizing some laser systems. These systems may not be ones in our electronics though, but instead those used in advanced sensors for finding chemicals and explosives, as well as biomedical research and more.
Source: University of Texas at Austin