Ohmic Dissipation‐Assisted Complex Amplitude Hologram with High Quality

Abstract

Tailoring the phase and amplitude of electromagnetic waves has drawn great attention in the microwave, terahertz, and even optics domains. However, the existing method for simultaneous control of these two essential properties suffers from inadequate efficiency and narrow bandwidth, especially for microwave devices. Here, a strategy of overcoming this difficulty is proposed by introducing the ohmic sheet into a Fabry–Pérot‐like cavity. The arbitrary phase modulation can be realized by changing the geometric parameters and the orientation of elliptical split resonance ring; via changing the intensity of ohmic dissipation, the amplitude can be continuously adjusted from 0 to 1. Its most significant advantage is arbitrary wide‐band complex‐amplitude modulation without introducing cross‐polarization crosstalk and backward scattering field interference. To verify its feasibility, three phase‐amplitude holographic imaging ​prototypes at 12, 14, and 16 GHz are designed. Both the simulated and measured results manifest the excellent performances of the proposed metasurface, demonstrating the excellent performances with a remarkable signal‐to‐noise ratio and low root‐mean‐square error. This proposed strategy provides an alternative method to control the phase and amplitude arbitrarily, which not only realizes high‐quality holography but also paves a way for random beamforming and so on.

Full Complex‐Amplitude Engineering by Orientation‐Assisted Bilayer Metasurfaces

“…Compared with phase-or amplitude-only meta-elements, [26][27][28][29][30][31][32][33] complex-amplitude meta-elements have attracted extensive interest due to their ability to independently and flexibly manipulate the two important optical parameters, i.e., amplitude and phase. In the current state of knowledge, there are several methods to realize complex-amplitude modulation by metasurfaces: changing the angle between two arms of the V-shaped nanostructure with different lengths, [34] changing the size and orientation angle of a single nanobrick, [35][36][37][38][39] changing the opening size and orientation angle of C-shaped nanostructure, [40][41][42][43][44] changing the orientation angle between two arms of X-shaped nanostructure, [45] changing the length/width of arm and orientation angle of cross-shaped nanostructure, [46][47][48][49] and changing the orientation angles of multi-nanostructure metaatom, [50][51][52][53][54] etc. However, these methods either change the size of nanostructures thus requiring high-accuracy fabrication, or integrate several nanostructures into a unit-cell thus reducing the pixel-resolution of meta-elements.…”

Smart Metasurface for Active and Passive Cooperative Manipulation of Electromagnetic Waves

“…Simultaneously, metasurfaces, an artificial material for arbitrary passive control of EM waves, have been investigated widely. A series of noticeable functionalities, including polarization conversion, − vortex beams, − holograms, − cloaks, and so on, , have been explored and achieved by meticulous design. Although metasurfaces exhibit excellent capabilities for light field modulation, the functions of a single metasurface are still limited.…”

Transmission Reflection Integrated Programmable Metasurface for Real‐Time Beam Control and High Efficiency Transmission Polarization Conversion

“…With the development of metasurfaces, some profound physical effects have been fulfilled, which are unavailable by naturally occurring materials. [1][2][3][4][5] Furthermore, metasurfaces exhibit tremendous promise for multifarious applications, including flat lens, [6,7] beam controller, [8][9][10] polarizer, [11][12][13] absorber and cloak, [14,15] hologram imager, [16][17][18] etc. However, the majority DOI: 10.1002/andp.202200368 of the previous metasurfaces can only implement one particular function, which cannot satisfy the multiplying demand for multifunctional devices.…”