New Approach to Superlens Devices Overcomes Limitations
3 September 2013
Researchers from the A*STAR Institute of High Performance Consulting in Singapore have developed a new device that can overcome the limitations posed by traditional lenses when it comes to redirecting beams of incoming light to focus and make them meet at a particular point.
The team, led by Zhengtong Liu, applied numerical modeling to develop the “superlens” system, which is a silver nanostructure embedded in glass designed to improve the interaction between light and matter. The device consists of two separate components, a nanoantenna and a superlens. The nanoantenna resembles the radio-frequency antennas, which track TV-carrying signals, but its size has been reduced so that it can tally with the wavelength of optical radiation. The superlens, comprising a thin plate of silver, is intended to direct the light detected by the antenna into an imaging plane.
The optical response of the device was modeled to an incoming beam of red light and the dimensions of the structure were then changed to ensure maximum enhancement in electric field. As a result, the researchers managed to demonstrate that a 20-nanometer thick superlens, separated by 34 nanometers from an antenna consisting of two silver ellipse, could boost the electric field of light by a factor of 250.
Using nanoantennas to focus light is not a novel approach, but thanks to the deployment of superlens the method has been enhanced to cope with the distortions caused by the optical properties of the material, Liu said.
The model is tipped to become a valuable tool for optical detection systems and to find application in biomedical and chemical sensing devices, Liu added.