Wei Li

Metasurfaces capable of spin-selective transmission have emerged as a promising platform for achieving optical chiral effects, addressing the limitations inherent in conventional threedimensional chiral structures. In this study, we propose a novel planar metasurface design that facilitates the generation of strong intrinsic chirality and spin-selective transmission by utilising quasi-bound states in the continuum (quasi-BICs), induced by intentional symmetry breaking in the structure. By carefully tuning the asymmetry parameter, we can precisely modulate the circular dichroism (CD). The maximum CD observed exceeds 0.97, demonstrating nearly perfect chirality. Moreover, we highlight the critical role of intrinsic loss in the chiral transmission process, which plays a key part in controlling the quality factor of the chiral quasi-BIC. Importantly, the underlying principles and design strategies, which were verified at microwave frequencies, are readily adaptable to higher-frequency domains such as terahertz and infrared. This chiral metasurface holds great potential for applications such as polarisation multiplexing in microwave communication, chiral molecular detection in the terahertz range, and infrared imaging based on circular polarisation.

Next‐generation wireless networks are expected to utilize limited radiofrequency (RF) resources more efficiently. Currently, the wireless communication systems require an extremely large number of RF chains and hence suffer from prohibitive complexity, hardware cost, and severe energy consumption. Tailoring the electromagnetic (EM) responses by metasurface greatly expands one′s capabilities to manipulate EM waves in a controlled manner. In this work, we developed a prototype of a metasurface‐based EM wave splitter with the contribution from the corresponding receiving antenna array and the designed spectrum reconstruction algorithm to achieve the wireless signal reception in a simplified way. This approach enables instantaneous capture of both frequency‐domain and time‐domain signals from the incident carrier wave, allowing a single chain to effectively receive modulated EM waves across a broad frequency range. By eliminating the need for conventional complex analog or digital circuits for demodulation, this strategy is a potential technique in the development of next‐generation wireless communication technologies.

This article used far-field light source to investigate the focal length of the short focal length, multifocal metalens. The feasibility of the scheme was analyzed by using imaging simulation. In addition, the relative error between far-field imaging method and collimated laser measurement was analyzed. The data results show that the relative error is 0.49%, as the point light source located 2000mm away, for ideal test lens with focal length of 10mm. An optical system composed of double lenses was constructed to measure the focal length of a metasurface with four focal points. The experimental results show that the system can determine the focal position within a step of 0.1mm.

Technological advancements have enabled the active control of electromagnetic waves. Metalenses, known for their precision in wavefront shaping and functional versatility, represent a breakthrough in optical modulation. This study addresses the challenge of achieving dual-wavelength multifunctionality in metalens design. We developed and experimentally validated metalenses with polarization dual-function multiplexing at discrete mid-wave infrared wavelengths, demonstrating high phase fidelity and functional versatility. In addition, the proposed design method was extended to long-wave infrared wavelengths, showcasing its adaptability to different application scenarios. The application of spatial multiplexing significantly enhanced the performance of the metalenses, providing a promising solution for efficient and compact optoelectronic devices.

Metalenses have excellent modulation capabilities in terms of phase, amplitude, and polarization of light, significantly reducing the size and complexity of imaging systems, and showing great application prospects. However, like traditional optical meta-atoms, ordinary metalenses suffer from a significant chromatic aberration problem because it is difficult to design the phase distribution for different wavelengths on a single-layer metalens. To address this, various methods for correcting chromatic aberration in metalenses have been proposed and demonstrated, such as spatial multiplexing, material hybridization, and increasing the cross-sectional diversity of metalens meta-atoms. In this paper, a novel design method is used, which expands the parameter space by increasing the cross-sectional diversity of the metalens meta-atoms to provide the phase required for focusing different wavelengths, combined with particle swarm optimization for phase compensation. The multi-level metalens designed by this method achieves a constant and approximate focal length in the visible wavelength range of λ = 450–650 nm, with a polarization-independent absolute focusing efficiency of about 17%, and a numerical aperture (NA) of 0.31 for a lens diameter of 100 μm. This improves the imaging quality.

The research on MEMS wireless sensing technology adapted to strong power frequency electromagnetic field environments is of great significance to our energy security, economic society, and even national security. Here, we propose a subwavelength cross-meandering resonator (0.49λ₀ × 0.49λ₀) to simultaneously achieve power frequency electromagnetic field shielding and wireless communication signal transmission. The element size of the resonator is only λ₀/11, which is much smaller than that of previous works. In the resonator, a resonance mode with the significant near-field enhancement effect (about 180 times that at f = 1 GHz) is supported. Based on the self-made shielding box experimental setup, the measured shielding effectiveness of the resonator sample can reach more than 33 dB. Moreover, by integrating the cross-meandering resonator with the MEMS sensor, a wireless communication signal can be successfully transmitted. A dual-function cross-meandering resonator integrated with sensors may find potential applications in many military and civilian industries associated with strong power frequency electromagnetic fields.

Vibration energy harvesting has received much attention as a new type of power solution for low-power micro/nano-devices. However, VEH (vibration energy harvester) based on PVDF (polyvinylidene fluoride) piezoelectric materials have a low output power and energy conversation efficiency due to the relatively low piezoelectric constant, coupling coefficient, and dielectric constant. For this reason, we design a vibration energy conversion power supply, which consists of a VEH with a PVDF piezoelectric thin film planar array vibration structure and an energy harvesting circuit for regulating the electric energy of multiple sources. Furthermore, our solution was validated by simulations of structural dynamics in COMSOL and equivalent circuits model in Multisim. From the circuitry simulation results, the output current and the charging period increase and decrease, doubling, respectively, for each doubling of the number of array groups of films. Moreover, the solid mechanics simulation results show that the planar array structure makes the phase and amplitude of the input vibration waves as consistent as possible so that the same theoretical enhancement effect of the circuitry model is achieved. An identical experimental test was implemented with vibration conditions of 75 Hz-2.198 g. The fabricated harvester quickly charged the 22 V-0.022 F ultracapacitor bank to 5 V in 24 min. The maximum open circuit voltage and output power, respectively, were 10.4 V and 0.304 mW. This maximum charging power was 11.69 times higher than that of a single film. This special power supply can replace batteries to power low-power electronics deployed in vibrating environments, thus reducing the maintenance costs of equipment and environmental pollution rates.

Metalens has the advantages of high design freedom, light weight and easy integration, thus provides a powerful platform for infrared detection. Here, we numerically demonstrated a broadband achromatic infrared all-dielectric metalens over a continuous 800 nm bandwidth, with strong environmental adaptability in air, water and oil. By building a database with multiple 2π phase coverage and anomalous dispersions, optimizing the corrected required phase profiles and designing the sizes and spatial distributions of silicon nanopillars, we numerically realized the design of broadband achromatic metalens. The simulation results of the designed metalens show nearly constant focal lengths and diffraction-limited focal spots over the continuous range of wavelengths from 4.0 to 4.8 μm, indicating the ability of the designed metalens to detect thermal signals over a temperature range from various fault points. Further simulation results show that the metalens maintains good focusing performance under the environment of water or oil. This work may facilitate the application of metalens in ultra-compact infrared detectors for power grid faults detection.

Metalenses provide a powerful paradigm for mid-infrared (MIR) imaging and detection while keeping the optical system compact. However, the design of MIR metalenses simultaneously correcting chromatic aberration and off-axis monochromatic aberration remains challenging. Here, we propose an MIR doublet metalens composed of a silicon aperture metalens and a silicon focusing metalens separated by a fused silica substrate. By performing ray-tracing optimization and particle-swarm optimization, we optimized the required phase profiles as well as the sizes and spatial distributions of silicon nanopillars of the doublet metalens. Simulation results showed that the MIR doublet metalens simultaneously achieved chromatic and off-axis monochromatic aberration reduction, realizing a continuous 400 nm bandwidth and 20° field-of-view (FOV). Thanks to its planar configuration, this metalens is suitable for integration with CMOS image sensor to achieve MIR imaging and detection, which has potential application in troubleshooting and intelligent inspection of power grids. This work may facilitate the practical application of metalens-integrated micro/nanosensors in intelligent energy.

Microwave sensors with low cost and high compatibility show great potential in the areas of environmental monitoring, food safety, and biomedical diagnostics. However, small microwave sensors using asymmetric antenna structures exhibit large fabrication difficulties or low figure of merits (FOMs). Here, we propose the Fano-resonant spiral dipole antenna (~ 0/13). In the antenna, a Fano resonance with a narrow bandwidth (~ f0/640) and high spectral contrast (C 1.0) is supported. In particular, an antenna array is used to improve the transmission efficiency (5-fold enhancement). Based on the Fano-resonant spiral dipole antenna, ultrahigh FOM microwave sensors are successfully realized. The Sensing FOM of the sensors can reach up to 252 RIU-1 and 172 RIU-1, respectively, which are more than 9 times those of the other sensors.