Reconfigurable Metasurface: A Systematic Categorization and Recent Advances

Considering the rapid progress of theory, design, fabrication and applications, metasurfaces (MTSs) have become a new research frontier in microwave, terahertz and optical bands. Reconfigurable metasurfaces (R-MTSs) can dynamically modulate electromagnetic (EM) waves with unparalleled flexibility, which has led to a great surge of research in recent years. Numerous R-MTSs with powerful capabilities and various functions are being proposed explosively. Based on the five dimensions of EM waves, this review proposes a unified model to describe the interactions among R-MTSs, EM waves and EM information and suggests an information bit allocation strategy to categorize different types of R-MTSs systematically. Recent advances in R-MTSs and 1-bit and 2-bit elements manipulating different wave dimensions are reviewed in detail. Finally, this review discusses the future research trends of R-MTSs. R-MTSs with diverse dimensions and functions may propel the next generation of communication, detection, sensing, imaging and computing applications.