A versatile metasurface platform based on phase change materials (PCMs) is provided to realize dynamic switching between edge detection and imaging without the assistance of a 4f imaging system. The metasurface consists of a periodic arrangement of unit structures which consists of a Ge2Sb2Se4Te1(GSST) nanofin on a silicon substrate. The dynamically switchable performance results from the combination of the geometric phase and two independent propagation phases that are provided by the composed phase-change material meta-atoms in amorphous and crystalline states. The average cross-polarized transmission coefficients are 0.77 and 0.42 in the amorphous and crystalline states. In order to verify the feasibility of the design, simulation and theoretical calculation of the designed switchable metasurface are carried out in crystalline state and amorphous state respectively, which show excellent imaging and edge detection results. The proposed metasurface and its working principle have potential applications in biomedical imaging and defect detection.ect detection.

The spherical aberration is an important factor affecting the resolution power of super-oscillatory telescopic systems. The reason is that the spherical aberration leads to a high sidelobe in the field of view of the intensity point spread function, which reduces the resolution of the system. In this paper, the effect of the spherical aberration on imaging in a super-oscillatory telescopic system is analyzed and the allowable range of the primary spherical aberration is determined. Based on the principle of optical super-oscillatory and the optimization method of linear programming, a super-oscillatory telescopic system is designed. A resolution of 0.68 times the Rayleigh criterion can be achieved under a working wavelength of 532 nm. A mathematical model for quantitative analysis of the super-oscillatory telescopic system with the spherical aberration is established. The system can distinguish the three-slit target under the interference of the primary spherical aberration with a root mean square (RMS) no more than 0.041 times wavelength. The imaging effect of the narrow band working wavelength in the spherical aberration system is analyzed. This paper has potential applications in optical measurement, environmental monitoring, super-resolution telescope, and other fields.

As an artificial micro-nano device, metasurfaces can precisely manipulate the propagation and phase of light beams. Vortex beams with different polarization vector properties possess unique optical field distribution characteristics, and the use of metasurfaces to generate complex vector vortex fields has increasingly broad research prospects. This article classifies materials for producing vector vortex beams with metasurfaces and introduces the research progress of metal metasurfaces, all-dielectric metasurfaces, and intelligent metasurfaces in vector vortex beam generation and control. We elaborate on the principles of modulating incident wavefronts using different phase theories and the characteristics of different vector vortex beams generated by metasurfaces, and explore the relationship between the two. Additionally, we summarize the advantages of using metasurfaces instead of traditional optical devices to generate vector vortex beams, and look forward to the challenges and possibilities of vector field control research using metasurfaces with different materials in the future.

Aiming at the problems of narrow working frequency band and low near field imaging efficiency in metasurface holographic imaging technology, this paper proposed the principle and model of optimization of achromatic broadband metasurface hologram imaging. A deep learning network model based on the depth image prior (DIP) is proposed for single-target passive metasurface hologram design, and achromatic broadband metasurface hologram imaging is achieved. Numerical simulation and experimental results have proved that the designed holographic imaging device can achieve good achromatic imaging effect in the 9 GHz~11 GHz frequency band, and has great potential application in the field of holographic imaging and broadband functional device design.

As a technology that combines spectral information with spatial information, spectral imaging has been widely concerned in scientific research and engineering applications. The optical field can be modulated efficiently by designing and optimizing the metasurfaces with subwavelength scale features. This article reviews the research progress of spectral imaging based on metasurfaces in recent years. Compared with traditional spectrometers, the compact spectrometers based on metasurfaces have the advantages of smaller volume and simpler optical path, and have greater application potential in small devices. According to different imaging mechanisms, spectral imaging based on metasurfaces can be divided into superdispersion, narrowband filter and broadband filter. The research progress of each imaging mechanism is introduced in detail, and then the application in practical scenarios is summarized. Finally, the development direction and application prospect of spectral imaging of metasurfaces are prospected.

Metasurfaces can manipulate the physical parameters of electromagnetic waves, including polarization, amplitude, and phase. The development of micro-nanofabrication technology further promotes the application prospects of metasurfaces in fields such as display, imaging, sensing, anti-counterfeiting, and optical modulation. However, most metasurfaces lack dynamic modulation, which restricts their scope of application. In recent years, the research on dynamic metasurfaces has made some progress. This review mainly introduces several mechanisms for dynamic metasurfaces, including electrical, thermal, optical, mechanical, and chemical modulations, and summarizes the research progress in the dynamic metasurfaces. In addition, this review also outlines the applications of dynamic metasurfaces in fields such as imaging, display, and optical modulations, and highlights their significance and prospects. Finally, this review summarizes the main problems and future development directions of currently tunable metasurfaces.

Metasurface can precisely modulate the fundamental properties such as polarization, amplitude, frequency, and phase of optical waves at the subwavelength scale. Based on this background, we propose and experimentally verify a multifunctional metasurface image display technology enabled by merging spatial frequency multiplexing and near- and far-field multiplexing. In near- and far-field multiplexing, the orientation degeneracy of nanostructures is introduced to combine geometric phase modulation and light intensity modulation, which leads to independent coding of near-field grayscale image and far-field holographic image displays by using simulated annealing algorithm. In spatial frequency multiplexing, different spatial frequency components of two images are added together to generate a hybrid image for hologram design. Since people receive different spatial frequency parts when the observation position changes, both high-frequency and low-frequency images can be easily distinguished. In our experiment, three independent images (a grayscale image, a high-frequency image and a low-frequency image) can be displayed simultaneously at different distances, which explains that our multifunctional metasurface has enhanced information storage capacity. This work provides a new path for multifunctional metasurface design, and possesses broad applications in optical encryption, optical anti-counterfeiting, and many other related fields.

Surface wave (SW), as a kind of information or energy transportation platform, can find important applications in on-chip optical devices and systems. However, the efficient and free control from near-field SW to far-field propagation wave still suffers from fundamental challenges in the field of on-chip photonics. This paper starts with an introduction of the basic principles for far-field radiation. Then it reviews the approaches to control the multiple parameters (e.g., phase, amplitude, and polarization state) of the SW’s radiation field based on the metasurface, as well as the complex far-field wavefront manipulation of the surface wave, such as the directional radiation, far-field focusing, special beam excitation, and holographic imaging. Finally, the main challenges and future developments of far-field radiation control of SWs are summarized.