![]() In addition to the observation of exciting physical phenomena, metamaterials have found wide applications in engineering due to their excellent performance, including novel antennas 32, 33, microwave components 34 and satellite communications. Hence, many exciting and unusual phenomena that do not occur in conventional media have been realized in metamaterials and/or metasurfaces, such as negative refraction 3, perfect imaging 12, invisibility cloaking 9, 10, 13, 14, 15, 16, 17, optical and radar illusions 18, 19, electromagnetic concentrators 20 and rotators 21, microwave and optical black holes 11, 22, 23, anomalous reflections and transmissions 24, 25, optical vortex 24, 26, broadband light bending 27, photonic spin Hall effect 28, polarization traffic controls 29, 30, and polarization rotations 31. Governed by the transformation optics 9, 10 and other physical principles 11, this unique flexibility in design makes metamaterials and metasurfaces very powerful in controlling the electromagnetic waves. Because of the flexible designs of meta-atoms and their arbitrary arrangements, the effective medium parameters can be tailored to have extreme values 3, 4, high inhomogeneity 5, 6 and strong anisotropies 7, 8. The subwavelength nature of metamaterials and/or metasurfaces enables them to be described by effective medium parameters (for example, electric permittivity, magnetic permeability, index of refraction and impedance) 1, 2. The proposed concepts and entropy control method will be helpful in new information systems (for example, communication, radar and imaging) that are based on the coding metasurfaces. The coding metasurface is demonstrated to enhance the information in transmitting messages, and the amount of enhanced information can be manipulated by designing the coding pattern with different information entropies. We introduce geometrical entropy to describe the information of the coding pattern (or coding sequence) and physical entropy to describe the information of the far-field pattern of the metasurface. ![]() We establish an analytical connection between the coding pattern of an arbitrary coding metasurface and its far-field pattern. Here we propose to measure the information of a coding metasurface using Shannon entropy. However, the studies of metamaterials or metasurfaces are mainly limited to their physical features currently, there is a lack of viewpoints on metamaterials and metasurfaces from the information perspective. ![]() Because of their exceptional capability to tailor the effective medium parameters, metamaterials have been widely used to control electromagnetic waves, which has led to the observation of many interesting phenomena, for example, negative refraction, invisibility cloaking, and anomalous reflections and transmissions. ![]()
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