Two-dimensional control of light with light on metasurfaces

The ability to control the wavefront of light is fundamental to focusing and redistribution of light, enabling many applications from imaging to spectroscopy. Wave interaction on highly nonlinear photorefractive materials is essentially the only established technology allowing the dynamic control of the wavefront of a light beam with another beam of light, but it is slow and requires large optical power. Here we report a proof-of-principle demonstration of a new technology for two-dimensional (2D) control of light with light based on the coherent interaction of optical beams on highly absorbing plasmonic metasurfaces. We illustrate this by performing 2D all-optical logical operations (AND, XOR and OR) and image processing. Our approach offers diffraction-limited resolution, potentially at arbitrarily-low intensity levels and with 100 THz bandwidth, thus promising new applications in space-division multiplexing, adaptive optics, image correction, processing and recognition, 2D binary optical data processing and reconfigurable optical devices. Metasurfaces: new approach for modifying light with light A new way to dynamically control light in two dimensions—the interaction of light beams on a plasmonic metasurface—has been demonstrated. Traditionally, nonlinear optical materials are used to dynamically modify one light beam by another, but this is slow and requires intense beams. Now, researchers at the University of Southampton in the UK present a fundamentally different approach that involves using a highly absorbing metasurface. It has the advantages of offering diffraction-limited resolution, femtosecond-scale response times and the ability to use low-intensity beams. Light–matter interactions are enhanced and surpressed by constructive and destructive interference of two light beams at the metasurface. Using this effect, the researchers demonstrate a simple optical computer that can perform logical operations between images. The method could be used in a range of applications including reconfigurable optical devices and all-optical image processing.