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.

A composite fiber optic sensor based on a misaligned peanut-shaped structure and the single-mode fiber–multimode fiber–single-mode fiber (SMS) structure is proposed for simultaneous strain and temperature measurements. The misaligned peanut-shaped structure is formed by introducing a certain core-offset during fusion splicing. Through a simulation analysis of the sensor, the optical field distribution of the sensor structure under different offset amounts is obtained. The experimental results demonstrate that the sensor achieves a maximum strain sensitivity of −48.21 pm/µε with an offset of 35.61 µm under a strain range of 0–600 µε and a maximum temperature sensitivity of 124.29 pm/°C at a 24.35 µm offset with a temperature range of 35–95 °C. Meanwhile, the sensor with a 35.61 µm offset has two resonance peaks that are selected for simultaneous measurements, with strain sensitivities of −48.21 pm/µε and −47.04 pm/µε and temperature sensitivities of 75.71 pm/°C and 84.29 pm/°C, respectively. Therefore, the simultaneous measurement of the strain and temperature can be achieved through a matrix method, demonstrating that the sensor possesses a dual-parameter sensing capability for the strain and temperature.

Remote sensing image segmentation is essential for urban planning, environmental monitoring, and disaster assessment but is challenged by scarce pixel-level annotations, domain shifts, and the difficulty of segmenting spectrally similar land cover classes. Existing methods struggle to address these issues comprehensively. Supervised approaches like UNetFormer require extensive labeled data and have limited generalization. Foundation models like SAM enable zero-shot segmentation but are constrained by high inference overhead, limiting their practical use in remote sensing. Self-supervised models like DINO capture domain-specific features but lack the global priors and generalization capabilities of large-scale foundation models, reducing their effectiveness in complex remote sensing scenarios. To overcome these limitations, FFSNet is proposed as a novel framework that integrates a lightweight MobileSAM encoder with a DINOv2 self-supervised encoder pretrained on remote sensing data. Its core innovation, the adaptive feature fusion module, balances general visual priors and domainspecific representations using attention-based dynamic weighting. Additionally, a modified category mask decoder extends binary output to multi-class segmentation using learnable prototype vectors. Experiments on three benchmark datasets validate the effectiveness of FFSNet. It achieves a mIoU of 55.4 % on LoveDA, surpassing D2lS, a mF1 of 88.3 % on ISPRS Potsdam, outperforming AerialFormer, and a mF1 of 91.6 % on Vaihingen, while using only 44.7 M parameters-a 50 % reduction compared to D2lS. FFSNet establishes a new paradigm for efficient domain adaptation in foundation models, offering superior segmentation accuracy with reduced computational costs, making it highly practical for large-scale remote sensing applications.

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.

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.

Topological materials often exhibit significant nonlinear optical (NLO) property variations at phase transition points. ZnNiAl-layered double hydroxides (LDHs) are promising due to their exceptional structural tunability. In this study, we investigate the high-temperature topological transformation of ZnNiAl-LDHs and the impact on the ultrafast carrier dynamics and NLO properties. It was found that in the topological state formed at 450 °C, spinel oxides ZnAl2O4 and NiAl2O4 were generated, which contribute to enhanced coupling interactions among the metal oxides. In addition, the optimized distribution of ordered and disordered nanodomains, along with the presence of more self-trapped states, improves electronic transition rate. The synergistic effect of the features enables faster recovery times and superior NLO properties across the three topological states. Specifically, the fast and slow response times are as short as 169 fs and 952 fs, respectively. Under pulsed laser excitation with a central wavelength of 1534 nm, a pulse duration of 905 fs, and a repetition rate of 11.17 MHz, the effective nonlinear absorption coefficient and third-order NLO polarizability coefficient reach −(0.70 ± 0.02) cm MW−1 and −(7.26 ± 0.21) × 10−10 esu, respectively. When employed as a saturable absorber, ZnNiAlOx-450 exhibits excellent filtering effects, thereby enabling tunable multi-wavelength continuous-wave and mode-locking operation in an Er-doped fiber laser. This work provides critical insights into leveraging topological phase transitions for advanced optoelectronic devices.

A polyvinyl alcohol (PVA)-coated optical fiber humidity sensor for respiratory monitoring is proposed. The humidity sensor forms a fiber Mach–Zehnder interferometer (MZI) by bending the single-mode fiber (SMF) coated with PVA. The refractive index of PVA coatings varies with changes in relative humidity (RH), causing phase changes in higher-order modes and resulting in shifts in the transmission spectrum. The sensor exhibits excellent dynamic humidity response performance (92.8 ms for response time and 63.6 ms for recovery time), realizing a humidity sensitivity of −1.927 nm/%RH within the humidity range of 86.1% to 92.2%. Compared to the balloon-shaped fiber optic sensor based on polydimethylsiloxane (PDMS) coating previously proposed by our research group, the PVA coating facilitates easier surface composite on the fiber, exhibits faster response speed, and its humidity response range is more suitable for respiratory monitoring. Ultimately, the sensor was encapsulated within a mask to enable human respiration monitoring functionality.

A highly sensitive pH sensor based on a tapered single-mode optical fiber (SMF) working at the dispersion turning point (DTP) is proposed, with calcium alginate hydrogel coated on its surface. The tapered SMF is prepared using a two-step tapering method, and the pH sensor is fabricated by coating the surface of the tapered SMF with calcium alginate hydrogel. Experimental results demonstrate that within the pH range of 7.03-8.45, the sensor exhibits the highest sensitivity at the DTP, with a sensitivity of 115.6 nm/pH. Furthermore, this sensor boasts benefits, including excellent repeatability and rapid response time. Compared with other sensors, the proposed pH sensor demonstrates superior pH sensitivity, simple structure, and low cost, making it highly promising for applications in seawater monitoring and biomedical fields.

This study proposes a cascade-type fiber curvature sensor with bowknot-type taper and a tapered fiber structure based on intermodal interference. The proposed sensor comprises two bowknot-type tapers prepared by fiber fusion splicing using single-mode fibers, and the tapered structure is added by fixed-point tapering. Experimental results show that when the tapered structure has a pulling cone length of 0-2500 mu m, the sensitivity of the sensor increases alongside the pulling cone length; furthermore, for pulling cone lengths of 3000 mu m and 3500 mu m, sensor sensitivity tends to be stable. The maximum sensitivity reaches-22. 50 nm/m(-1) in a curvature range of 3. 4072-6. 0881 m(-1) for a pulling cone length of 2500 mu m. This structure has both high sensitivity and high stability, which effectively solves the problem of temperature cross-sensitivity and simultaneously simplifies the sensor manufacturing process, improving its compactness and reducing the production cost.

This study proposes an axial strain fiber-optic sensor based on the vernier effect. The sensor is composed of two tapered single-mode fibers (TSMFs) connected in parallel through two 3-dB fiber couplers. Each TSMF functions as an individual Mach-Zehnder interferometer (MZI) due to the phase difference between the core mode and cladding modes introduced by its structure. In this parallel configuration, one MZI serves as the sensing element and the other as the reference element for the Vernier effect. Experimental results indicate that these parallel Mach-Zehnder interferometers (PMZIs) with differing free spectral ranges (FSRs) exhibit high sensitivity to axial strain. A maximum axial strain sensitivity of 552.14 p.m./mu 8 is achieved by the PMZIs in the range of 0-240 mu 8. Additionally, the sensor shows good repeatability, making it suitable for measuring physical quantities such as micro-strains.

A respiratory monitoring sensor based on a balloon-shaped optical fiber is proposed. The sensor consists of a single-mode fiber (SMF) coated with polydimethylsiloxane (PDMS) bent into a balloon shape to form a fiber optic Mach–Zehnder interferometer. The sensor’s sensitivity to temperature enables monitoring of breathing status by recognizing the temperature changes that occur during human respiration. By adjusting the bending radius of the balloon-shaped SMF, high-order modes can be effectively excited to interfere with the core mode. Due to the high thermo-optic coefficient and thermal expansion coefficient of PDMS itself, the balloon-shaped fiber optic sensor can achieve temperature sensitivity. The experimental results show that the temperature sensitivity is −166.29 pm/°C in a temperature range of 30 °C to 60 °C. Finally, the proposed sensor was mounted into a respiratory mask to monitor different breathing states (normal, fast, slow, and oral–nasal breathing transitions) and breathing frequencies.

Reliable and high-quality wind power prediction results are significant for wind energy utilization and power system management. This article delves into the cutting-edge application of Large Language Models (LLMs) in the domain of wind power generation forecasting, leveraging their zero-shot learning capabilities to circumvent conventional computational constraints. Inspired by the success of language-based pre-training models, this study posits a question: Can these models be adapted to address the challenges of wind power generation forecasting? To examine this, we offer a novel methodology for precise wind power generation forecasting that employs prompt-based techniques. This approach involves converting numerical inputs and outputs into prompts, framing the forecasting task as a conversational interaction. Such a method allows for the direct application of language models in the prediction process. Our findings indicate that, compared to conventional wind power forecasting models, the prompt-based approach offers distinct advantages, particularly when it integrates background knowledge with multivariate inputs. This revolutionary method accelerates the modeling process, decreases the obstacles to adopting complex predictive models, and provides new routes for the research and implementation of renewable energy forecasting. Future endeavors will concentrate on enhancing the model's performance and broadening its applicability to other renewable energy forecasting domains.

A new cascaded structure is proposed and investigated as a sensor for simultaneous measurement of refractive index (RI) and temperature. This sensor is fabricated by periodically embedding the coaxial dual-waveguide fiber in the no-core fiber to form a long-period fiber grating (CEN-LPFG). The simulation analysis of the transmission spectrum of the proposed CEN-LPFG sensor is carried out to obtain the appropriate period. The periodic arrangement induces the transmission spectrum with two resonance peaks. Therefore, the simultaneous measurement of RI and temperature is realized by observing the wavelength shift of the two peaks. The total length of the sensing unit is only 4.4 mm. Experimental results show that the RI sensitivities of the two resonance peaks of the CEN-LPFG sensor are 183.62nm/RIU and 278.44nm/RIU with the RI range of 1.33-1.41, respectively. Meanwhile, the temperature sensitivities of the two resonance peaks of the CEN-LPFG sensor are -27.67pm/°C and 37.5pm/°C with the temperature range of 20-100 °C, respectively. The feasibility of the CEN-LPFG sensor has been experimentally demonstrated for simultaneous measurement.

An axial strain and temperature sensor based on a tapered seven-core fiber (SCF) operating at the dispersion turning point (DTP) is proposed. The tapered SCF sensor with DTP was fabricated by the one-step tapering method, and its axial strain characteristics and temperature characteristics were simulated and experimentally investigated. The experimental results show that the tapered SCF sensor operates near DTP with the highest axial strain sensitivity and temperature sensitivity, consistent with the simulation results. The maximum axial strain sensitivity of the tapered SCF sensor is 391.2 pm/mu epsilon in the range of 0-300 mu epsilon, and the maximum temperature sensitivity is 6.44 nm/degrees C in the range of 30-70 degrees C. The sensor is highly sensitive to axial strain and temperature. It is promising for measuring physical quantities such as weak strain and temperature.

Glucose sensors are critical in label-free optical biosensing. This study explored the use of nonadiabatic tapered micro/nano optical fibers (NATOFs) with varying diameters ( $\mathbf{10}\ \boldsymbol{\mu}\mathbf{m}, \mathbf{9}\ \boldsymbol{\mu} \mathbf{m}, \mathbf{7}\ \boldsymbol{\mu}\mathbf{m}$ , and $\mathbf{6}\ \boldsymbol{\mu} \mathbf{m}$ ) for glucose detection. These fibers were constructed using the Mach-Zehnder interferometry (MZI) principle and the fiber fusion-drawing taper technique. The optical fibers were used to measure refractive indices in glucose solutions with mass fractions ranging from 2 wt% to 20 wt%, where the refractive indices varied between 1.3346 and 1.3608. The findings revealed that decreases in waist diameter substantially enhanced sensor sensitivity, with recorded values of 1851.9 nm/RIU, 2025.8 nm/RIU, 2563.3 nm/RIU, and 2646.4 nm/RIU. Additionally, reducing the diameter of the waist region decreased the free spectral range, enhancing the sensor's accuracy in measuring glucose concentration. This study highlights the potential of micro/nanofiber optic technology in biosensor design, offering new insights for biomedical detection, food quality monitoring, environmental surveillance, and chemical analysis.

Spectral beam combining (SBC) has the potential to further increase the power irrespective of the limited power of single laser, and to maintain the near-diffraction-limited beam quality. However, the total power, the beam quality, and the spectra of SBC are significantly affected by the crosstalk effect attributed to the "smile" effect. Although crosstalk mitigation methods have been proposed, with the increasing laser number in dense spectral beam combining, the crosstalk caused by the spectral dispersion of single laser may hinder the further improvement of SBC. Fortunately, SBC with a dual-grating external cavity has shown the potential to narrow the linewidth of the laser array. However, its physical model has not been previously reported, restricting the comprehensive understanding of the system. Here, we present the physical model of SBC with the dual-grating external cavity. Using this physical model, the mitigation of spectral dispersion in single laser by the dual-grating configuration is investigated in depth. The influence of grating parameters on the combined beam, including its spectra and beam quality, is also analyzed. Furthermore, the alignment of the dual-grating, significantly affecting the beam quality and spectra of the combined beam, can be used for system optimization. We hope this model can provide valuable insights and guidance to the spectral dispersion management in SBC. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

This paper presents a novel malposition fusion splice cascade single mode, graded index multimode, and single mode fiber (MS-SMS) structure for simultaneous measurement of strain and temperature. The MS-SMS sensor consists of a 4-period single mode fiber graded refractive index multimode fiber splice with a total length of 4.8 mm. Moreover, higher order cladding patterns are excited by malposition fusion splice. The theoretical analysis simulations are in agreement with the experimental results. Experimental validation showed the high strain and temperature sensitivity of the sensor. The sensor has two resonant dips with strain sensitivities of 7.6 pm/με and -8.7 pm/με, respectively. And the sensitivities of the two resonance depressions reached 48 pm/°C and 55.4 pm/°C, respectively.