The advent of metasurface technology has revolutionized the field of optics and photonics in recent years due to its capability of engineering optical wavefronts with well-patterned nanostructures at subwavelength scale. Meanwhile, inspired and benefited from the tremendous success of the “lab-on-fiber” concept, the integration of metasurface with optical fibers has drawn particular interest in the last decade, which establishes a novel technological platform towards the development of “all-in-fiber” metasurface-based devices. Thereby, this review aims to present and summarize the optical fiber-integrated metasurfaces with the current state of the art. The application scenarios of the optical fiber metasurface-based devices are well classified and discussed accordingly, with a brief explanation of physical fundamentals and design methods. The key fabrication methods corresponding to various optical fiber metasurfaces are summarized and compared. Furthermore, the challenges and potential future research directions of optical fiber metasurfaces are addressed to further leverage the flexibility and versatility of meta-fiber-based devices. It is believed that the optical fiber metasurfaces, as a novel all-around technological platform, will be exploited for a large range of applications in telecommunication, sensing, imaging, and biomedicine.

As a vital sign of human, ballistocardiography (BCG) signal is widely used to indicate the health status of an individual. It can be captured by optical fiber sensor in a non-invasive way. Besides, some significant physiological information, such as heart rate (HR) and respiration rate (RR), can also be extracted from BCG signal. As a medical instrument characterized by low power consumption, no interference, no invasion and the capability of real-time health monitoring, optical fiber sensor provides an effective solution to health care monitoring. However, when long-term monitoring of HR and RR is required for patients, it is necessary to collect a large amount of BCG data, which incurs a considerable amount of time and labor costs. To solve this problem, a novel deep learning model is proposed in this paper, namely ELA. Long-short term memory (LSTM) has the capability to memorize long-distance information states. According to this method, the improved empirical mode decomposition (EMD) algorithm (VEMD) is applied to convert the complex problem of HR and RR time series prediction into multiple sub-problems with relatively simple intrinsic mode function (IMF) component sequence prediction. Then, the proposed ELA model is adopted to model the HR and RR sub-sequences decomposed by VEMD. Accordingly, the results of IMF component subsequence prediction are obtained, with all the prediction results linearly summed to obtain the final prediction result. Moreover, experimental results are obtained to demonstrate the superiority of ELA and the R ² is 0.9946, indicating the excellent performance of the proposed model in the assessment and prediction of vital signs.

We have proposed and experimentally validated a novel approach to suppress interference fading in phase-sensitive optical time-domain reflectometry ( ϕ -OTDR) by employing dual-polarization orthogonal frequency division modulation (OFDM) signals within the fractional Fourier domain. The fractional OFDM signals for orthogonal polarization states consist of multi-subcarriers that are linear frequency modulation (LFM) signals with identical sweep bandwidths but different initial frequencies. By combining fractional Fourier transform (FrFT) algorithm with multiple input multiple output (MIMO) processing, each subcarrier with specific frequency modulation (FM) slope and overlapped sweep bandwidth can be not only compressed but also distinguished, even when affected by polarization evolution. Consequently, the complementary backscattering signals extracted can be utilized to concurrently eliminate interference fading and polarization fading after the synthesis by MIMO-FrFT. The proof-of-concept experiment has demonstrated that this approach can reduce intensity fluctuations from over 70 dB to 15 dB. The lowest intensity of the synthesized trace is 6.7 dB higher than the noise floor, resulting in fading free performance. The fading-free ϕ -OTDR is experimentally verified through dynamic measurements under single-frequency or sweep-frequency vibrations, attaining a sensing distance of 10 km and a sub-meter spatial resolution of 50 cm. Moreover, the block sliding window FrFT scanning is proposed to reduce complexity consumption of data processing, leading to 99.2% decrease in multiplication compared to FrFT scanning sample by sample. The sweep bandwidths of LFM signals for orthogonal polarization states completely overlap, resulting in ultra-high spectrum efficiency.

Recently, near-field optical tweezers integrated on a chip based on silicon on insulator (SOI) have attracted more attention and are promising for biological and chemical analyses. Here we propose a low-loss Si waveguide tapered from 800 nm width to 200 nm over 4 m, then back to 800 nm again, with a high intensity gradient in the electric field to trap microparticles whose diameters vary from 1 m to 5 m. The high transmittance allows for cascading the traps along the direction of light propagation. Optical forces in all three dimensions are analyzed around a high-stiffness potential well obtained. Moreover, a dynamic model is applied to analyze the motion processes of microparticles.

The ability to achieve comprehensive control over all Stokes parameters, including both the state of polarization (SoP) and the degree of polarization (DoP), is fundamental to advancements in quantum optics, imaging, and optical communications. While metasurfaces have demonstrated remarkable capabilities in polarization manipulation, existing designs typically rely on locally periodic unit cells and deterministic phase profiles, limiting their flexibility in controlling both SoP and DoP simultaneously. Here, we introduce the generalized lattice approach for metasurface design, which enables the decoupling of structural parameters from the full-Stokes polarization response. Our approach introduces a spatially global but structurally disordered arrangement, constructed on a generalized lattice framework. This framework enables the flexible placement of an arbitrary number and type of meta-atoms within a generalized lattice, where the relative quantity ratios among different meta-atoms serve as a new design degree of freedom. This decoupling enables the azimuthal and elevation angles of the SoP on the Poincaré sphere to be governed by the in-plane rotation and size of individual meta-atoms, while the DoP is controlled independently via the quantity ratio. This establishes a direct and analytically tractable mapping between metasurface geometry and polarization space, offering new physical insights into metasurface-based polarization control. A computationally efficient algorithm optimizes the metasurface arrangement, achieving a polarization similarity (evaluated by Stokes Euclidean Distance) of 0.93 in theory and 0.90 in experiment. Our findings demonstrate that the generalized lattice approach provides an effective and versatile route to full-Stokes polarization control with greater flexibility than conventional metasurface designs.

The ability to achieve comprehensive control over all Stokes parameters, including both the state of polarization (SoP) and the degree of polarization (DoP), is fundamental to advancements in quantum optics, polarization imaging, and optical communications. While metasurfaces have demonstrated remarkable capabilities in polarization control, existing approaches often struggle to simultaneously manipulate SoP and DoP with high flexibility. Here, we introduce a paradigm shift in metasurface-based polarization engineering by proposing a globally engineered disordered metasurface that enables a one-to-one correspondence between structural parameters and the full-Stokes polarization space. Unlike conventional metasurfaces that rely solely on unit-cell-level deterministic phase profiles, our approach incorporates a statistical design principle, introducing a spatial statistical parameter: the meta-atom quantity ratio. By uniformly distributing two distinct types of meta-atoms with controlled ratios, we effectively decouple the design parameters, enabling independent control over all Stokes parameters. Specifically, the azimuthal and elevation angles of the SoP on the Poincaré sphere are governed by the rotation and size of individual meta-atoms, while the DoP is precisely tuned through global disorder engineering via the quantity ratio of the meta-atoms. This approach establishes a direct mapping between metasurface design and polarization space, revealing new physical insights into disorder-assisted polarization control. A computationally efficient algorithm optimizes the metasurface arrangement, achieving a polarization similarity (evaluated by Stokes Euclidean Distance) of 0.93 in theory and 0.90 in experiment. Our findings advance the development of metasurfaces that harness disorder as a functional design strategy, enabling enhanced flexibility in full-Stokes polarization engineering.