Guoxiang Dong

Ultra-broadband and high-efficiency polarization conversion metasurface with multiple plasmon resonance modes*

In this paper, we present a novel metasurface design that achieves a high-efficiency ultra-broadband cross polarization conversion. The metasurface is composed of an array of unit resonators, each of which combines an H-shaped structure and two rectangular metallic patches. Different plasmon resonance modes are excited in unit resonators and allow the polarization states to be manipulated. The bandwidth of the cross polarization converter is 82% of the central frequency, covering the range from 15.7 GHz to 37.5 GHz. The conversion efficiency of the innovative new design is higher than 90%. At 14.43 GHz and 40.95 GHz, the linearly polarized incident wave is converted into a circularly polarized wave.

A multi-band spoof surface plasmon polariton coupling metasurface based on dispersion engineering

We propose a metasurface to achieve multi-band helicity dependent directional spoof surface plasmon polaritons (SPPs) coupling for circular polarized light in the microwave range. Our work shows that the coupling frequencies of spoof SPPs on the gradient metasurface are related to the dispersion relations of the metasurface, which indicate the desired coupling frequency can be manipulated by dispersion engineering. The proposed metasurface has counter-directional phase gradients for different helicity incidents and possesses multiple different dispersion relations by carefully designing the geometric parameters of each unit, which leads to the multi-band helicity-controlled directional spoof SPPs coupling. Both the simulation and experiment show that the multi-band helicity-controlled directional spoof SPPs coupling is achieved with a high efficiency.

Ghost Imaging Based on Deep Learning

Even though ghost imaging (GI), an unconventional imaging method, has received increased attention by researchers during the last decades, imaging speed is still not satisfactory. Once the data-acquisition method and the system parameters are determined, only the processing method has the potential to accelerate image-processing significantly. However, both the basic correlation method and the compressed sensing algorithm, which are often used for ghost imaging, have their own problems. To overcome these challenges, a novel deep learning ghost imaging method is proposed in this paper. We modified the convolutional neural network that is commonly used in deep learning to fit the characteristics of ghost imaging. This modified network can be referred to as ghost imaging convolutional neural network. Our simulations and experiments confirm that, using this new method, a target image can be obtained faster and more accurate at low sampling rate compared with conventional GI method.

Wideband polarization-independent anomalous reflection metasurface with multiple resonance modes

An ultra-thin metasurface is proposed to realize wideband polarization-independent anomalous reflection. The sub-wavelength resonator can produce different resonance modes, which are the result of the combined effect of dielectric and the metallic structure. The gradient metasurface is done by six discrete orientation of the local sub-wavelength resonator which provides a phase gradient. The simulation and measured results show that 9GHz bandwidth of the anomalous reflection is achieved.

Design of a reconfigurable polarization converter based on RF switches

A reconfigurable polarization converter that enables transparent polarization tunable is presented. The converter has simple metal structure and the transmitted wave can be tuned between linear polarization (LP) and circular polarization (CP) by adjusting the state of the switches inserted into the structure. The simulated and experimental transmission parameters were obtained to verify the polarization tunability for LP incident waves at two ideal states of the switches.

Wideband polarization-independent anomalous reflection mediated by metasurface

An ultra-thin metasurface is proposed to realize wideband polarization-independent anomalous reflection. The gradient metasurface is done by 6 discrete orientation of the local sub-wavelength resonator, which provides a phase gradient. The simulation and measured results show that 9 GHz bandwidth of the anomalous reflection is achieved.

Wideband helicity dependent spoof surface plasmon polaritons coupling metasurface based on dispersion design

The surface plasmon polaritons (SPPs) have many potential application due to their local field enhancement and sub-wavelength characteristics. Recently, the gradient metasurface is introduced to couple the spoof SPPs in microwave frequency band. One of the most important issue which should be solved is the narrowband of spoof SPPs coupling on the gradient metasurface. Here, the metasurface is proposed to achieve the wideband helicity dependent directional spoof SPPs coupling for circular polarized light. Our research show that the coupling frequency of spoof SPPs on the gradient metasurface is determined by the dispersion of the metasurface, so the coupling frequency can be controlled by dispersion design. The careful design of each cell geometric parameters has provided many appropriate dispersion relations possessed by just one metasurface. The wave vector matching between the propagating wave and the spoof SPPs has been achieved at several frequencies for certain wave vector provided by the metasurface, which leads to wideband spoof SPPs coupling. This work has shown that wideband helicity dependent directional spoof SPPs coupling has been achieved with a high efficiency. Hence, the proposed wideband spoof SPPs coupling presents the improvement in practice applications.