Constructing Metastructures with Broadband Electromagnetic Functionality

Abstract

Electromagnetic metastructures stand for the artificial structures with a characteristic size smaller than the wavelength, which may efficiently manipulate the states of light. However, their applications are often restricted by the bandwidth of the electromagnetic response of the metastructures. It is therefore essential to reassert the principles in constructing broadband electromagnetic metastructures. Herein, after summarizing the conventional approaches for achieving broadband electromagnetic functionality, some recent developments in realizing broadband electromagnetic response by dispersion compensation, nonresonant effects, and several trade‐off approaches are reviewed, followed by some perspectives for the future development of broadband metamaterials. It is anticipated that broadband metastructures will have even more substantial applications in optoelectronics, energy harvesting, and information technology.

Realizing Colorful Holographic Mimicry by Metasurfaces

“…Metasurfaces, [14][15][16][17][18][19] an emerging 2D photonic platform made of subwavelength arrays of artificially designed scatters, have demonstrated many unique features that are unavailable in conventional materials. [17,20,21] Because of the exceptional ability to modify the phase, [14][15][16]22,23] polarization, [24][25][26] and amplitude [27][28][29][30][31][32] of reradiated light, metasurfaces have enabled a number of applications, including broadband wave-plates, [33,34] polarization rotators, [25,26] perfect absorbers, [27,35] metalenses, [36][37][38][39] plasmonic color display, [28,[40][41][42] holograms, [43][44][45][46][47] and so on. Among them, as one important direction, tunable and reconfigurable meta-devices have attracted much attention.…”

Invisible surfaces enabled by the coalescence of anti-reflection and wavefront controllability in ultrathin metasurfaces

“…We note that the GAMs demonstrated here are tailored to the surface shape, the material parameters and the properties of the incident waves like the incident angle, frequency, and polarization. By employing the abundant degrees of freedom in the multilayer design, we are able to realize the GAMs for both polarizations and enhance operating bandwidth by further structure optimization [11][12][13]45 . The other limitations could also be relieved by exploring active control in the metasurface design 14,24 , which has now been widely explored.…”

Construct Achromatic Polymer Microlens for High‐Transmission Full‐Color Imaging

“…It is well known that metasurface can accurately modulate the phase, [14][15][16] amplitude, [17,18] and polarization state [19][20][21] of light by selecting proper subwavelength resonant units on the surface. [22][23][24][25] Comparing to the traditional refractive or diffractive lenses, metalens can achieve the same or even better functions with greatly miniaturized size and significantly mitigated weight. [26][27][28][29][30][31][32][33][34][35][36] With precise control of the phase profile, metalenses are free of spherical aberration, which have been successfully demonstrated in terahertz, infrared, and visible regions.…”