The development of surface plasmon resonance imaging (SPRi) systems capable of simultaneously achieving high throughput, high temporal resolution, and precise quantification remains a significant challenge. Conventional wavelength-scanning SPRi systems are fundamentally limited by a speed-fidelity trade-off: acquiring a complete, high-resolution spectrum for accurate resonance tracking inherently requires long acquisition times, severely restricting temporal resolution to the order of seconds. To overcome this bottleneck, we report a novel SPRi platform based on a synergistic hardware-algorithm co-design. We introduce a programmable multi-wavelength LED array as the illumination source, eliminating mechanical tuners and enabling flexible, full-field spectral scanning. Crucially, we develop a cascaded optimized-sampling algorithm that strategically reduces the required spectral measurements per cycle from over fifty to just six. This innovation, augmented by real-time spectral deconvolution with Tikhonov regularization to correct for source broadening, allows the system to maintain high spectral fidelity while reaching a temporal resolution of 0.48 s. The integrated system achieves a bulk refractive index sensitivity of ∼5478 nm/RIU, a wide dynamic range (>0.0148 RIU), and a refractive index resolution of ∼1.8 × 10⁻⁶ RIU. In a multiplexed bioassay, the platform successfully performed real-time, high-throughput kinetic monitoring of IgG/Protein A interactions, achieving a detection limit of 0.026 µg/mL. This work breaks the traditional speed–fidelity trade-off in wavelength-scanning SPRi through a synergistic hardware–algorithm co-design. The system realizes mechanical-tuner-free, full-field continuous spectral scanning and achieves real-time, high-throughput imaging capability, offering a robust and cost-effective platform for applications such as rapid drug screening and dynamic cellular interaction studies.

In this letter, the fGLIA (filtered generalized lock-in amplifier) algorithm is introduced to fiber-optic vibration measurement. The filtering procedure of the original fGLIA algorithm is changed, making it more suitable for dynamic signal measurement. Theoretically the proposed demodulation scheme is not influenced by the zeros of the Bessel functions, and can keep a good performance in a wide range of modulation depth. It is compared with PGC-Arctan demodulation scheme by simulations and experiments, showing better robustness to modulation depth error and larger range of applicable modulation depth. The experimental total harmonic distortion of demodulation results remains at about -53dB for the proposed method, while distortions may occur at certain modulation depths for PGC-Arctan.

Conventional wavelength-modulated surface plasmon resonance imaging (WSPRi) systems rely on costly spectrometers or tunable filters, limiting their accessibility. We report a low-cost, high-performance WSPRi system that replaces these components with an array of six monochromatic LEDs. A Smoothness-Constrained Reconstruction algorithm accurately reconstructs SPR spectra from the LED data, effectively suppressing noise and avoiding spectral broadening. Our system achieves a refractive index resolution of 1.65x10(-6 )RIU, and we demonstrate its high-throughput capability with a parallel immunoassay. This work provides a robust and cost-effective platform that makes high-sensitivity SPR sensing viable for broader applications.

This paper presents a novel phase-modulated surface plasmon resonance imaging (SPRi) method. It is based on a programmable LED array and computational spectral reconstruction, and is designed to simultaneously achieve high sensitivity, wide dynamic range, rapid measurement, and low system cost. The system employs an incoherent LED light source coupled with a computational phase extraction algorithm. This approach eliminates the need for traditional interferometric structures and physical modulation devices, thereby effectively overcoming the inherent trade-off between sensitivity and dynamic range in conventional phase-sensitive SPR. Experimental results demonstrate that the system attains a refractive index resolution of 6.96×10⁻⁷ RIU, a dynamic range of 1.48×10⁻² RIU, and a temporal resolution of 2.5 seconds, enabling parallel, real-time monitoring across six independent microfluidic channels. Kinetic analysis of antigen-antibody binding processes yielded a detection limit of 4.29 ng/mL, with binding affinity parameters consistent with those obtained from commercial instruments. This work provides a high-performance, cost-effective SPRi solution for high-throughput and highly sensitive biomolecular interaction analysis.

A U-shaped displacement and temperature sensorbased on tapered single-mode fiber (TSMF) is proposed. Thesensor is fabricated by bending the TSMF into a U-shape toexcite higher-order modes, thereby forming a Mach-Zehnderinterferometer (MZI). Through simulation and analysis of the transmission spectrum of the U-shaped sensor, obtain a suitableU-shaped bending radius and waist diameter. When the waistdiameter of the TSMF is 40 mu m, and the bending radius of theU-shape is 1355 mu m, the sensor exhibits two interference dips.By monitoring the wavelength shifts of two interference dips, simultaneous measurement of displacement and temperature is achieved. The experimental results show that the U-shaped sensorachieves high displacement sensitivity of 1.367 and 2.771 nm/mu min the 0-50-mu m displacement range, respectively. Besides, the sen-sor achieves temperature sensitivities of 20.71 and 31.43 pm/degrees Cin the range of 30 degrees C-90 degrees C, respectively. The proposed U-shaped sensor has the advantages of compact structure, simple preparation, and high sensitivity, making it an ideal candidate for the future simultaneous measurement of displacement and temperature in structural health monitoring.

In this Letter, we propose a dynamic time warping (DTW)-based nonlinear spatial position correction method for OFDR-based distributed sensing, which overcomes the fundamental failure of conventional cross-correlation-based position correction under ultra-large strain conditions (>1%). The proposed method exploits DTW's ability to establish an adaptive, point-by-point nonlinear mapping between the reference and sensing Rayleigh backscattering (RBS) spectra, thereby simultaneously compensating for localized intra-window scale distortion (spectral stretching/compression) and global inter-window positional drift. Experimental results demonstrate robust strain measurement up to 20000 με (2%) over a 50 m fiber while maintaining 2 mm spatial resolution, representing a twofold expansion of OFDR's measurable strain range. This advancement addresses the long-standing limitation of insufficient high-precision strain demodulation capability under extreme deformation conditions.

Fiber interferometers are widely used in precision measurements, yet phase-noise suppression over the mHz-kHz band remains a key bottleneck. Here, a specialty hollow-core photonic bandgap fiber (HC-PBGF) is introduced as the sensing arm to reduce temperature-induced phase noise. Comparative measurements show that, relative to a solid-core polarization-maintaining fiber (PMF) interferometer, the HC-PBGF interferometer achieves an ∼18 dB reduction in phase-noise power spectral density (PSD) in the mHz-Hz band while maintaining an ∼7 dB advantage in the Hz-k Hz band, which is qualitatively consistent with the simplified theoretical prediction. These results support the development of HC-PBGF-based broadband low-noise fiber interferometry.

Abstract Conventional surface plasmon resonance imaging (SPRi) relies on relative resonance-shift measurements and laborious multipoint calibration, rendering it incompatible with disposable-chip and point-of-care scenarios. Here, we report a Hadamard-encoded spectral compressive reconstruction (HSCR) platform coupled with a lightweight one-dimensional convolutional neural network (1D-SPRNet). By reframing chip-scale spatial nonuniformity as an in situ data-augmentation mechanism, the system generates ∼20,000 pixel-wise training spectra from a single measurement cycle and converts six compressed CMOS frames into quantitative refractive-index changes (ΔRIU) using only six multiplexed LED measurements. By outputting physical refractive-index units rather than arbitrary resonance shifts, the system eliminates the need for exhaustive chip-specific calibration: a minimal two-point Langmuir fit suffices for quantitative immunodetection. We demonstrate high-fidelity spectral recovery (Pearson correlation >0.999) and cross-chip generalization using NaCl refractive-index standards. In a rabbit IgG/goat antirabbit IgG model, the pretrained 1D-SPRNet achieves linear regression R2 = 0.996 in phosphate-buffered saline and R2 = 0.987 in 10-fold diluted human serum, with relative errors within ±7% in phosphate-buffered saline and recoveries ranging from 88.7% to 101.1% in 10-fold diluted human serum, along with negligible nonspecific adsorption. This integration of compressive spectral encoding with end-to-end deep regression enables high-throughput, real-time, minimal-calibration multiplexed biosensing.

With the ongoing advancement of modern society, the demand for high‐sensitivity and real‐time detection sensors continues to grow, thereby accelerating the development of sensing technologies. Surface plasmon resonance (SPR) sensing has emerged as a valuable technique owing to its real‐time, label‐free, and rapid detection capabilities. However, its limited sensitivity and detection range remain major challenges in optical sensing. MXenes, as two‐dimensional (2D) materials, have garnered considerable attention owing to their large specific surface area, high electrical conductivity, excellent biocompatibility, and stability, establishing them as one of the most prominent materials for optical sensing. This paper first provides a concise overview of the properties of MXenes, followed by an analysis of various SPR sensor configurations and performance improvement strategies. Finally, it summarizes the latest advances in the application of MXenes in SPR sensors, discusses their potential for enhancing sensing performance, and offers a perspective on development directions. Despite being in its early stages, MXene‐based SPR sensing has demonstrated significant potential for expanding into broader applications.

We propose a Rayleigh-Brillouin hybrid distributed acoustic sensing that employs a pre-written Brillouin dynamic grating (BDG) in a polarization-maintaining fiber and a single-shot chirped pulse. Rayleigh backscatter (RBS) and BDG reflection are excited simultaneously, and theoretical analysis shows that both channels can be demodulated via time-to-frequency mapping. The recovered acoustic signals are then combined using an adaptive filtering algorithm that leverages the high sensitivity of the RBS channel and the large measurement range of the BDG channel. This strategy provides high dynamic range and sensitivity across the entire acoustic detection bandwidth, overcoming the low-frequency sensitivity limitations of RBS. Experiments demonstrate a minimum detectable strain of 2.6 nε at 1 mHz with temperature compensation.

Dynamic sensing and high-accuracy measurement constitute two core technical bottlenecks in conventional Brillouin optical time-domain analysis (BOTDA) sensors, which inherently involve a mutually restrictive trade-off rooted in their operational principles. This study presents an ultra-low-noise Brillouin random-access dynamic sensor based on a chirped pulse. By leveraging random-access functionality and single-shot measurement capability, the sensor realizes a dynamic single-end BOTDA configuration where performance is solely constrained by the pulse time-of-flight. Ultra-low-noise detection is achieved by removing modulator timing jitter, optimizing the chirp rate, and reducing laser phase noise, and using cross-correlation demodulation to mitigate uncertainties arising from transient waveform distortions. Consequently, the sensor delivers an average strain resolution of 3.42 nε/Hz (with a minimum of 2.66 nε/Hz), a sensor bandwidth of 25 kHz, and a spatial resolution of 10 m over a 1 km polarization-maintaining fiber. To date, it represents one of the most accurate Brillouin dynamic sensors reported in the literature, offering substantial application potential in critical fields such as civil structural health monitoring and oil/gas pipeline leakage detection.

A compact curvature and temperature simultaneous measurement sensor is proposed, which is the structure of core-offset seven-core fiber (SCF) embedding in the spliced long period fiber grating (LPFG). The spliced LPFG consist of periodically cascaded single-mode fiber (SMF) and multimode fiber (MMF). Through simulation analysis that the transmission spectrum with two resonance peaks is obtained, two peaks wavelength shift is observed to measure both curvature and temperature simultaneously. The sensor with compact length of 6.4 mm. The experimental results demonstrate that the curvature sensitivities of the sensor are 5.694 nm/m-1 and-22.255 nm/m-1 with the curvature range of 0.5326-1.8026 m-1, respectively. The two resonance peaks of the sensor have temperature sensitivities of are 49 pm/degrees C and 83 pm/degrees C, and the temperature range of 30-80 degrees C, respectively. Therefore, the simultaneous measurement of curvature and temperature can be achieved through a matrix approach, demonstrating the sensor possesses a dual-parameter sensing capability of curvature and temperature.

ABSTRACT The detection of ultra‐trace mercury ions (Hg 2 + ) is a critical step for environmental monitoring and risk assessment, yet conventional detection technologies suffer from weak interfacial refractive‐index perturbation and susceptibility to interference from non‐specific adsorption in multi‐ion matrices. To address these issues, this study fabricates a mercapto‐functionalized black phosphorene (BP‐SH) functional layer on the surface of the BK7–Au structure, which achieves enhanced interfacial electric field, amplified angular sensitivity, and sulfur‐site functionalization simultaneously. Experiments confirm that this novel sensor elevates the angular sensitivity from 135 deg/RIU to 265 deg/RIU, exhibits a stable response to Hg 2 + in the concentration range of 10 − 1 7 –10 − 1 3 M, and achieves an attomolar‐level LOD of 10 − 1 8 M. Comparative tests with other interfering heavy‐metal ions demonstrate that the designed sensor exhibits high selectivity toward Hg 2 + . Mixed‐ion and real‐water measurements further validate Hg 2 + discrimination in complex matrices. This research provides a novel sensing strategy for the ultra‐trace analysis of environmental mercury ions, effectively improving the sensitivity and selectivity of low ‐ concentration Hg 2+ detection.

An intensity-interrogated optical fiber hot-wire anemometer employing a cobalt-doped fiber Bragg grating (CD-FBG) is proposed and experimentally demonstrated. The CD-FBG absorbs light energy from a 1480 nm laser and turns into a u201Chot wireu201D with its temperature decreasing and therefore reflection spectrum blue-shifting with the airflow velocity. To achieve intensity interrogation, a wavelength-switchable narrow-linewidth probe laser is used, which makes the reflected optical power from the CD-FBG change monotonously with the airflow velocity in a certain measurement range. In the experiment, the high sensitivity of u22121248 u03BCW/(m/s) is achieved at the airflow velocity of 0.05 m/s. The measurement range is extended to 0 m/su20138.0 m/s by switching the probe laser wavelength. The response time and recovery time of the anemometer are 0.5 seconds and 0.6 seconds, respectively. The intensity interrogation scheme and simple structure of the anemometer probe greatly reduce the cost and make it a promising solution for high-precision airflow velocity measurement in many practical applications.

Significance New-generation specialty optical fibers, such as hollow-core fiber (HCF), multi-core fiber (MCF), and ultra-fine polarization-maintaining fiber (PMF), represent cutting-edge optical waveguide technologies manufactured using advanced materials and precision structural designs. These fibers overcome the limitations of traditional single-mode fibers in terms of bandwidth, nonlinearity threshold threshold, and environmental adaptability, becoming critical components in high-speed optical communications, high-precision fiber sensing, and emerging photonic systems. However, their complex internal structures and extreme optical properties present unprecedented challenges for performance evaluation and quality inspection. Particularly when local defects, mode coupling, or polarization decay occur within the fiber, these phenomena severely compromise system reliability yet remain undetectable by conventional centralized parameter measurement techniques. The rapid development of novel specialty optical fibers has also exposed the limitations of traditional centralized parameter measurement methods. Conventional fiber transmission parameter characterization techniques can only provide overall average parameters for the test sample, failing to precisely analyze the spatial distribution along the fiber length. In practical applications, localized defects, stress concentrations, microbends, polarization coupling, and inter-mode crosstalk within fibers and fiber devices are often the primary factors causing performance degradation and compromised system stability. The lack of high-resolution fiber distributed transmission parameter measurement capabilities may pose hidden risks for future large-scale deployments. With the development of various novel optical fibers for specialized applications, the requirements for distributed transmission parameter testing have become increasingly stringent. The extremely weak scattering signals in anti-resonant hollow-core fibers, the wide dynamic range in ultra-fine-diameter polarization-maintaining fibers, and the urgent need for long measurement distances and high spatial resolution pose significant challenges to existing distributed fiber measurement systems. Therefore, systematically reviewing the principles, progress, and performance limits of distributed testing technologies for novel specialty fibers is crucial to advancing the development of these fibers and their related applications. Progress Distributed measurement techniques for specialty optical fibers have evolved from single-dimensional, single-parameter measurements to multidimensional joint analysis and simultaneous multi-parameter decoupling. Multiple technical approaches collectively form the current framework for comprehensively characterizing the transmission parameters of novel optical fibers. Existing distributed testing techniques can generally characterize key optical parameters of novel specialty fibers, but their performance remains limited. Current mainstream approaches include Rayleigh scattering-based and polarization-dependent distributed testing. Rayleigh-based methods mainly employ optical time domain reflectometer(OTDR), optical frequency domain reflectometry (OFDR), and optical low-coherence reflectometry(OLCR). OTDR supports kilometer-to hundred-kilometer-scale measurements with meter-level resolution, whereas OLCR offers micrometer resolution with a very limited range. OFDR balances resolution and measurement distance, enabling high-resolution sensing over medium to long ranges, and is therefore well suited for specialty fiber inspection. Rayleigh scattering testing has undergone substantial improvements in sensitivity and dynamic range. Coherent detection and dual-polarization in-phase/quadrature(IQ) modulation have reduced the detectable scattering level to -150 dB/m, enabling distributed loss measurement of hollow-core fibers with extremely weak scatterings. Meanwhile, advanced signal processing-such as phase noise suppression and sweep nonlinearity correction-has significantly extended measurement range and resolution, allowing centimeter-level resolution over hundreds of kilometers in state-of-the-art systems. Distributed polarization measurement is a key development direction, especially for polarization-maintaining fibers and fiber-optic gyroscope loops. Techniques including P-OTDR, P-OFDR, optical coherence domain polarimetry(OCDP), and the recently proposed optical frequency domain polarimetry(OFDP) enables distributed extraction of birefringence and polarization crosstalk. While early systems suffered from low sensitivity and short range, recent advances in polarization-diversity detection and signal processing have greatly improved performance. Centimeter-level distributed birefringence measurement with similar to 10(-7) accuracy has been achieved over kilometer-scale fibers, and OFDP now offers over 100 dB dynamic range with measurement distances approaching 10 km, enabling a high-fidelity polarization crosstalk characterization. In recent years, distributed fiber testing instruments have advanced rapidly. Commercial high-resolution spectrometers and polarization analyzers now meet the demands of novel fibers, while domestically developed systems have reached or even exceeded imported equipment for certain metrics, promoting independent precision optical inspection. These advances have enabled representative applications: centimeter-resolution distributed loss measurements in hollow-core fibers reveal splices, structural nonuniformities, and scattering distributions over short to ultra-long distances; distributed birefringence and polarization crosstalk measurements in ultra-fine-diameter polarization-maintaining fibers and sensing coils expose fabrication defects, winding stress, and structural asymmetry. Collectively, these results indicate that distributed testing has evolved from a diagnostic method into a core enabling technology for specialty fiber innovations. Conclusions and Prospects Distributed optical measurement has emerged as a core technology for characterizing the transmission properties of specialty optical fibers. By enabling continuous spatial characterization of parameters such as loss, birefringence, and polarization crosstalk, distributed measurement technology overcomes the inherent limitations of traditional lumped-parameter testing. This technique provides critical support for fiber design optimization, defect localization, and reliability assessment, proving particularly well-suited for hollow-core fibers and ultra-fine-diameter fibers with complex internal structures. Performance enhancement of distributed fiber testing systems remains a core research focus. Future efforts must strive to simultaneously achieve ultra-high sensitivity, ultra-wide dynamic range, long measurement distances, and high spatial resolution. Overcoming the trade-offs between these metrics is crucial for meeting the stringent testing requirements of next-generation specialty fiber systems. Highly integrated equipment and multi-parameter joint analysis represent a hot research field. Multi-parameter joint analysis and AI-assisted signal processing hold promise for realizing real-time, high-throughput, automated fiber evaluation systems. Distributed testing systems will gradually evolve into comprehensive fiber "health monitoring" platforms, supporting the large-scale deployment of specialty fibers in communication networks, precision sensing systems, and advanced photonic systems.

Frequency-modulated continuous-wave (FMCW) interferometry is a pivotal technique for high-resolution, noncontact distance measurement. However, enhancing its resolution typically requires a substantial laser tuning range, and a systematic framework linking signal quality to ultimate resolution remains underdeveloped. This article introduces an Arcsine (Asin) phase demodulation method based on peak feature reconstruction to achieve high-resolution FMCW interferometry with a relatively compact tuning range. The proposed method reconstructs the phase via peak detection and an arcsine operation, significantly improving the accuracy of demodulation per unit tuning range. Experimental validation demonstrates that with a tuning range of only 26 GHz, our approach enables absolute distance measurement over 0-1 m with submicrometer resolution and an accuracy of 0.86 mu m.

Symmetry-protected bound states in the continuum (SP-BICs) offer a promising approach for high-quality (Q) metasurface design due to their non-radiative properties. However, conventional isolated SP-BICs typically offer limited enhancement to Q and require extremely small symmetry-breaking perturbations to become excitable, presenting challenges in fabrication and practical deployment. This work proposes a novel approach to enhance the Q-factor of resonances by merging BICs, enabling the structure to sustain ultra-high Q-factor even under relatively large symmetry-breaking conditions. Specifically, a double-layer metasurface composed of two silicon nanopore arrays is designed. By tuning the interlayer distance, SP-BICs are effectively merged with Fabry-Perot-type BICs in parameter space, modifying the radiation behavior of the original SP-BICs. Results show that the merged BIC structure enhances the Q-factor by three orders of magnitude compared to isolated BICs. In sensing performance, the proposed structure achieves a refractive index sensitivity of 126 nm/RIU and an outstanding figure of merit surpassing 1.4 x 10(5) RIU-1, which substantially outperforms isolated BICs. Moreover, diverse high-Q modal features are observed in the wavelength-offset parameter space, offering new opportunities for multi-channel sensing and narrowband filtering applications.

The previous common understanding of chirped-pulse phase-sensitive optical time-domain reflectometry (CP-phi OTDR) was that the strain measurement range hinges on precisely matching the detection bandwidth to the chirp bandwidth. Increasing the shot-to-shot measurement range (SSMR) necessarily raises the sampling rate proportionally, posing significant challenges to signal processing and increasing sampling costs. This paper reveals that using only a detection bandwidth equivalent to a portion of the chirp bandwidth can achieve almost the same SSMR, with only a minor difference attributable to the statistical randomness inherent in Rayleigh scattering. Meanwhile, it shows noticeable degradation of sensitivity. The simulations reveal a balance point between detection bandwidth and sensitivity loss. At this balance point, sensitivity loss is threefold while saving one-third of the bandwidth. Beyond this point, further increasing the detection bandwidth yields diminishing sensitivity improvements, whereas reducing the detection bandwidth below this point leads to rapid sensitivity degradation. Experimental validation shifts this balance point to one-fourth, primarily due to measurement deviations. This study provides design guidelines for employing CP-phi OTDR cost-effectively in large SSMR applications with acceptable sensitivity loss, such as seismic or ocean wave monitoring.

A curvature sensor based on four-core fiber (FCF) capable of real-time pulse wave monitoring is proposed and experimentally validated. The sensor structure comprises one section of FCF and two sections of multimode fiber (MMF). The refractive index difference between the core and cladding of FCF and MMF, coupled with core diameter mismatch, enhances supermode excitation and mode coupling within the FCF. Static sensing experiments demonstrate that the sensor exhibits a maximum sensitivity of -87.735 nm/m-1 within a curvature range of 0 to 1.1703 m-1, with a temperature cross-sensitivity of -0.0004 m-1/degrees C. After encapsulation with polydimethylsiloxane (PDMS), the sensor maintains excellent mechanical properties, ensuring reliable long-term pulse measurement. Positioned at the radial artery on the wrist, the sensor enabled pulse wave monitoring across different individuals during various movement states. Furthermore, pulse wave monitoring is achieved at the three acupoints (Cun, Guan, and Chi) corresponding to traditional Chinese pulse diagnosis locations. This advancement significantly promotes the visualization and objectification of traditional Chinese pulse diagnosis, as well as the integration of Chinese and Western medicine.