Information metamaterials – from effective media to real-time information processing systems
Metamaterials have been characterized by effective medium parameters over the past decades due to the subwavelength nature of meta-atoms. Once the metamaterials are fabricated, their functions become fixed or tunable. Recently, the concept of digital metamaterials has been introduced, in which, for...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
De Gruyter
2019-03-01
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| Series: | Nanophotonics |
| Subjects: | |
| Online Access: | https://doi.org/10.1515/nanoph-2019-0006 |
| Summary: | Metamaterials have been characterized by effective medium parameters over the past decades due to the subwavelength nature of meta-atoms. Once the metamaterials are fabricated, their functions become fixed or tunable. Recently, the concept of digital metamaterials has been introduced, in which, for instance, the constitutive 1-bit meta-atom is digitalized as “0” or “1” corresponding to two opposite electromagnetic (EM) responses. The digital metamaterials set up a bridge between the physical world and the information world. More interestingly, when the digital meta-atom is programmable, a single metamaterial can be used to realize different functions when programmed with different coding sequences. Moreover, as the states of programmable meta-atoms can be quickly switched, it enables the wave-based information coding and processing on the physical level of metamaterials in real time. For these reasons, we prefer to call digital metamaterials with programmable meta-atoms as “information metamaterials.” In this review article, we introduce two basic principles for information metamaterials: Shannon entropy on metamaterials to measure the information capacity quantitatively and digital convolution on metamaterials to manipulate the beam steering. Afterwards, two proof-of-concept imaging systems based on information metamaterials, i.e. programmable hologram and programmable imager, are presented, showing more powerful abilities than the traditional counterparts. Furthermore, we discuss the time-modulated information metamaterial that enables efficient and accurate manipulations of spectral harmonic distributions and brings new physical phenomena such as frequency cloaking and velocity illusion. As a relevant application of time-modulated information metamaterials, we propose a novel architecture of wireless communication, which simplifies the modern wireless communication system. Finally, the future trends of information metamaterials are predicted. |
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| ISSN: | 2192-8606 2192-8614 |