Electromagnetic waves can be manipulated to result in many interesting physical phenomena, such as optical illusions. This is made possible by artificial metamaterials called metasurfaces.
In an article in Advanced Science, Prof. Wei Xiang Jiang and Prof. Tie Jun Cui from Southeast University, Prof. Cheng-Wei Qiu from the National University of Singapore, and their co-workers report a remote, light-controllable metasurface, which is characterized by digital coding.
The metasurface is composed of a digital unit cell having subparticles, along with a light-emitting diode light source and a photodiode array. By changing the intensity of the illumination onto the photodiode array, the reflected beams from the digital metasurface produce different radiation patterns corresponding to different digital coding sequences.
The far-field radiation patterns of the fabricated digital coding metasurface were measured using a horn antenna as the exciting source. At a light intensity of 0 lux, a single reflected beam occurs and the coding sequence consists entirely of zeros (“000000”). At 100 lux, two main reflected beams are observed and the coding sequence is “010101”. At a higher frequency, different radiation patterns are produced, serving as a proof-of-concept for this method.