A polarization-dependent metasurface that consists of nanobrick arrays with spatial varying dimensions in two orthogonal directions has shown independent phase control ability, which paves a new way to design a reconfigurable step-zoom lens with two different focal lengths depending on the polarization states of an incident beam. In this paper, we report a highly integrated step-zoom metalens with dual focal lengths based on double-sided metasurfaces sitting on a transparent substrate. By assigning the focal power and balancing the aberrations between the front and rear metasurfaces, a large field-of-view ( ± 20°) step-zoom metalens corrected for monochromatic aberrations was designed, and its high performance (nearly diffraction-limited image quality for both on-axis and off-axis imaging) was verified by full-wave numerical simulations. More interestingly, the image plane of the designed metalens keeps unchanged after the zoom switching, which will bring great convenience for practical applications. With the advantages such as ultra-compactness, flexibility, and simplicity, the proposed metalens indicates the potential in the fields that require highly integrated zoom imaging and beam focusing without optical and mechanical compensations.

We review our works on Fabry-Perot (F-P) interferometric fiber-optic sensors with various applications. We give a general model of F-P interferometric optical fiber sensors including diffraction loss caused by the beam divergence and the Gouy phase shift. Based on different structures of an F-P cavity formed on the end of a single-mode fiber, the F-P interferometric optical sensor has been extended to measurements of the refractive index (RI) of liquids and solids, temperature as well as small displacement. The RI of liquids and solids can be obtained by monitoring the fringe contrast related to Fresnel reflections, while the ambient temperature and small displacement can be obtained by monitoring the wavelength shift of the interference fringes. The F-P interferometric fiber-optic sensors can be used for many scientific and technological applications.

Subwavelength spatial control of phase using metasurfaces is attractive for practical applications such as flat lens, vector beam generator, ultrathin wave-plate and high-resolution holography. All-dielectric metasurfaces provide two phase modulation mechanisms, which are propagation phase dependent on the dimension of meta-atoms and geometric phase dependent on the orientation of meta-atoms. Recently, it was proposed that by combining geometric phase and propagation phase, arbitrary and independent phase profiles can be imposed on a pair of orthogonal polarizations. However, a succinct expression of phase change introduced during an arbitrary polarization conversion process has not been presented. Here, we derive the geometric phase for the general case of nonorthogonal polarization conversions. Through the numerical simulations of a metasurface orbital angular momentum generator under both circular and elliptical polarization illuminations, we verify our theoretical analyses. This work presents the mechanism of controlling polarization and phase of arbitrary polarizations using both geometric phase and propagation phase, which exhibits the potential to enrich the capacity of polarization multiplexed metasurfaces.

Optical neural network (ONN), integrating deep learning algorithms and optical computing (OC) hardware, are gradually emerging as a powerful tool for artificial intelligence (AI) computing. Metasurfaces (MSs) have infused new vitality into the development of ONN by leveraging their nanoscale structures to precisely manipulate optical field parameters. In recent years, MS-based optical neural networks (M-ONNs) have sparked an innovative trend in the OC field, significantly impacting the development of next-generation optical communication and networking technologies. This paper presents an overview of M-ONN, beginning with an introduction to its theoretical framework and various design approaches. Then, the latest research progress in the practical applications of M-ONN is reviewed, emphasizing the crucial role of direct laser writing (DLW) in the manufacturing process. Further discussion covers the potential applications of M-ONN in next-generation optical communication and networking. Lastly, the focus shifts to the industrial progress of M-ONN. With technology maturing and the industrial chain solidifying, M-ONN is transitioning from the laboratory to real-world applications, poised to become a catalyst for transformative developments in the next-generation optical communication and networking field.

The metasurface based beam‐steering devices with the advantages of large steering angles, arbitrary channels and ultra‐compactness have played an important role for data allocation and exchange in the optical wireless communication. However, the current metasurface based optical wireless communication systems are mainly on intensity modulation and direct detection (IM/DD), which shows a relative lower transmission capacity, lower received optical signal‐to‐noise ratio (OSNR) and complexity of system. In this study, a bidirectional multichannel optical wireless system enabled by a polarization independent metasurface with coherent modulation and reception is designed and experimentally demonstrated, which exhibits exclusive 100 Gbps coherent optical signals to multiusers with their own wavelengths, 2 m free space distance and field of view of 20° × 20°. In addition, the proposed system can support optical broadcasting system with capacity of 900 Gbps. The demonstrated metasurface assisted optical wireless communication system merges the optical coherent communication techniques and emerging concept of metasurface, which reduces the complexity and cost of the system while contributing a high transmission capacity, opening a new avenue for high performance optical wireless communications.