Zhuochao Wang

Metasurfaces enable a new degree of controlling electromagnetic (EM) wave by modulating subwavelength artificial structures. In this article, a reflection-type metasurface based on the modified Pancharatnam-Berry (P-B) phase elements is proposed to manipulate the reflected EM wave under oblique incidence. Based on the modified P-B phase, the desired linear phase gradient along the x-axis can be achieved at the interface of the metasurface by adjusting the rotation angle of the unit cells. When a circularly polarized EM wave illuminates on the metasurface obliquely, the anomalous reflected wave can be observed in a broad bandwidth with high efficiency, and the reflection angle can be predicted by the generalized snell's law. Two metasurfaces with different phase gradients are designed in this article. The simulated results agree well with the theoretical designs, showing outstanding ability to manipulate the propagation of the EM wave. With specific phase gradient of the proposed metasurface, the anomalous reflected wave can be bent to the same side of the normal with the incident wave, which means that negative reflection effect can be achieved. Our design provides a solution to manipulate reflected beam under oblique incidence with high conversion efficiency, which has great practical applications in medical imaging, communication technology, and energy harvesting.

Huygens metasurface, composed of electric and magnetic dipoles, can fully control the transmission and reflection coefficient in theory. In this paper, a multi-phase hologram utilizing Huygens metasurface is presented in microwave regime. Here, we focus on the achievement of holographic rotation around the origin of Cartesian coordinates and the center of images individually. The spatial rotation operations are realized with calculated phase distribution based on time-shifting operations and rotational invariance of Fourier transform. Our designs expand the route to realize more powerful manipulations of electromagnetic (EM) wave propagation for flexible and continuous control of holographic images.

Ordered mesoporous carbons (OMCs) were prepared using SBA-15 as the template and sucrose as the precursor. Various different mesoporous materials (CMK-3-80, CMK-3-90, CMK-3-100 and CMK-Na₂SiO₃-3-90) were synthesized employing different conditions. The pore structures and characteristics of the OMC materials were evaluated using XRD, SEM and nitrogen adsorption studies, respectively, and their adsorption properties towards phenol and dyes were investigated. The results showed that the order of the pore diameter in the mesoporous materials followed the sequence: CMK-3-100 > CMK-3-90 > CMK-3-80 > CMK-Na₂SiO₃-3-90. Adsorption experiments revealed that the mesoporous carbons prepared possessed larger adsorption capacities towards phenol and the Reactive dyes Methylene Blue (MB) and Rhodamine Blue (RB) relative to commercial active carbon. Adsorption kinetics experiments showed that the rates of adsorption of MB and RB onto CMK-3 differed in line with the difference in pore size. Furthermore, the adsorption kinetics of MB and RB onto CMK-3 could be well described by the pseudo-first-order kinetic model. The adsorption isotherms indicated that the equilibrium adsorption capacities of the two dyes onto CMK-3 were not the same and could not be correlated with either the relative magnitudes of the mesopore surface areas or the mesopore volumes.