A new technique can transform silver into any color of the rainbow. Northwestern University researchers used a focused ion beam technique on ultrathin metallic films to produce different colors. The method is a fast, inexpensive alternative to the color filters that are commonly used in electronic displays and monitors. It doesn’t require expensive nanofabrication techniques or materials and it can be completed in just half an hour.
The research, which is supported by the Air Force Office of Scientific Research, was published in ACS Photonics on January 28, 2015. The system involves a three-layer structure, with glass sandwiched between two layers of silver film that are thin enough to allow optical light to pass through. By varying the thickness of the glass, the researchers are able to filter and produce different colors. The structure also acts as a color absorber; when the bottom layer of silver is thicker, it traps light between the two metal layers.
The team demonstrated a narrow bandwidth super absorber with 97 percent maximum absorption, which could be used for optoelectric devices with controlled bandwidth, such as narrow-band photodetectors and light-emitting devices. Lead researcher Koray Aydin is also experimenting with changing the thickness of the materials and using different metals in order to design devices for other wavelengths of light, such as using an aluminum system to filter or absorb ultraviolet light.
Source: Northwestern | ACS Photonics