No abstract

Controlling the polarization state of electromagnetic waves is an important topic in microwaves due to the enormous application potential in radar technology and mobile communications. Here, we propose a programmable metasurface based on single-pole double-throw switches to realize multifunctional polarization conversions. A structure of the double-sided metallic pattern is adopted in the metasurface, in which a novel double-pole double-throw hub is achieved to guide the energy direction. Such a mechanism successfully induces multiple transmission channels into the metasurface structure for functional design. By controlling the states of the switches with a field programmable gate array, the x- and y-polarizations of the incident waves can be efficiently modulated into linear co- and cross-polarizations of transmitted waves, suggesting a higher degree of freedom on wave manipulations. The proposed metasurface can be developed as a near-field information encoder to transmit binary coding sequence according to the energy distribution. Character transmissions are realized by programming binary ASCII codes on the transmitted fields. Nine supercells on the metasurface can encode 9-bit binary information in one frame of near-field imaging, which can be switched in real time with high speed. We envision that this work will develop digital coding applications to control the polarization information.

Applying multiple physical fields to artificial manipulate electromagnetic waves is a highly stirring research. In this paper, we creatively combine light control with microwave scattering, realizing an optically coding metasurface for beam deflection based on anomalous reflection. A photoresistor and a voltage-driven module are connected to control each row of PIN-diode-loaded unit cells, endowing the reflection phase of the elements with a strong dependence on light. Owing to the high sensitivity of photoresistor, the digital element state “0” or “1” can be switched effectively via light variation sensed by the photoresistor. By modulating the light signal, the arrangement of digital elements can be reprogrammed, generating the specific scattering field. Therefore, the electromagnetic field can be determined by the spatial distribution of light, which induces the connect with the optical information and microwave field. The simulated and experimental results demonstrate the feasibility of our design. This light-steering approach provides a dimension for electromagnetic wave modulation.

In this paper, we propose a dual manipulation on wave-front in the X band based on a reconfigurable water-based metasurface. We design and test a metasurface integrated with a saline-water substrate and PIN diodes. We showed that the wave-front reflected by the metasurface can be modulated by both the degree of salinity and the diode pattern. With these two manipulating methods, the metasurface can not only control the amplitude of the scattered beams but also the beam deflection angles, which promises a more flexible and economical way to manipulate the wave-front. We provide two diode patterns to illustrate the performance. The experimental results agree well with our simulations, further verifying our designs. Superior than the conventional reconfigurable metasurfaces, the proposed metasurface combines both water salinity and diodes, which offers more possibilities in electromagnetic (EM) wave tailoring, as well as potential applications in sensing and detection.

The lack of systematic structural resolution makes it difficult to build specific transition-metal-atom-doped carbonized polymer dots (TMA-doped CPDs). Herein, the structure-activity relationship between Cu atoms and CPDs was evaluated by studying the peroxidase-like properties of GluÀ CuÀ CPDs prepared by using copper glutamate (Glu) with a CuÀ N 2 O 2 initial structure. The results showed that the Cu atoms bound to GluÀ CuÀ CPDs in the form of CuÀ N 2 C 2 , indicating that CuÀ O bonds changed into CuÀ C bonds under hydrothermal conditions. This phenomenon was also observed in other copper-doped CPDs. Moreover, the carboxyl and amino groups content decreased after copper-atom doping. Theoretical calculations revealed a dual-site catalytic mechanism for catalyzing H 2 O 2 . The detection of intracellular H 2 O 2 suggested their application prospects. Our study provides an in-depth understanding of the formation and catalytic mechanism of TMA-doped-CPDs, allowing for the generation specific TMA-doped-CPDs.