Soft polymer optical fiber(SPOF)has shown great potential in optical-based wearable and implantable biosensors due to its excellent mechanical properties and optical guiding characteristics.However,the multimodality c...Soft polymer optical fiber(SPOF)has shown great potential in optical-based wearable and implantable biosensors due to its excellent mechanical properties and optical guiding characteristics.However,the multimodality characteristics of SPOF limit their integration with traditional fiber optic sensors.This article introduces for the first time a flexible fiber optic vibration sensor based on laser interference technology,which can be applied to vibration measurement under high stretch conditions.This sensor utilizes elastic optical fibers made of polydimethylsiloxane(PDMS)as sensing elements,combined with phase generating carrier technology,to achieve vibration measurement at 50−260 Hz within the stretch range of 0−42%.展开更多
Battery safety has emerged as a critical challenge for achieving carbon neutrality,driven by the increasing frequency of thermal runaway incidents in electric vehicles(EVs)and stationary energy storage systems(ESSs).C...Battery safety has emerged as a critical challenge for achieving carbon neutrality,driven by the increasing frequency of thermal runaway incidents in electric vehicles(EVs)and stationary energy storage systems(ESSs).Conventional battery monitoring technologies struggle to track multiple physicochemical parameters in real time,hindering early hazard detection.Embedded optical fiber sensors have gained prominence as a transformative solution for next-generation smart battery sensing,owing to their micrometer size,multiplexing capability,and electromagnetic immunity.However,comprehensive reviews focusing on their advancements in operando multi-parameter monitoring remain scarce,despite their critical importance for ensuring battery safety.To address this gap,this review first introduces a classification and the fundamental principles of advanced battery-oriented optical fiber sensors.Subsequently,it summarizes recent developments in single-parameter battery monitoring using optical fiber sensors.Building on this foundation,this review presents the first comprehensive analysis of multifunctional optical fiber sensing platforms capable of simultaneously tracking temperature,strain,pressure,refractive index,and monitoring battery aging.Targeted strategies are proposed to facilitate the practical development of this technology,including optimization of sensor integration techniques,minimizing sensor invasiveness,resolving the cross-sensitivity of fiber Bragg grating(FBG)through structural innovation,enhancing techno-economics,and combining with artificial intelligence(AI).By aligning academic research with industry requirements,this review provides a methodological roadmap for developing robust optical sensing systems to ensure battery safety in decarbonization-driven applications.展开更多
Time division multiplexing(TDM)architecture is an important approach to creating sensor arrays for massive scale monitoring.But it is paradoxical for the TDM interferometric sensor array to keep a short delay fiber fo...Time division multiplexing(TDM)architecture is an important approach to creating sensor arrays for massive scale monitoring.But it is paradoxical for the TDM interferometric sensor array to keep a short delay fiber for high sensing resolution and meanwhile use low sampling rate for practical applications.In this paper,a phase matching sampling(PMS)paradigm is proposed to address the above contradiction.By matching the phase of the sampling clock with the delay fiber length,combining with multiple-pulses sampling strategy,the proposed PMS method can avoid collecting the redundant information,facilitating the decreasing of sampling rate as well as delay fiber length of the TDM sensing system.The proof-of-concept experiments on an 8-channel TDM interferometric system demonstrate that when the sampling rate is fixed at 20 MS/s,by applying the PMS algorithm,the delay fiber length can be shortened from 100 m to 1 m,compared with applying the conventional sampling method.It reduced the phase noise of the system by a factor of 10 at 1 mHz and by a factor of 50 at 1 Hz.The PMS algorithm for greatly reducing the sampling rate is expected to fuel the TDM interferometric sensor arrays for many applications.展开更多
The work describes a surface plasmon resonance(SPR)sensor that measures the liquid level and refractive index(RI)simultaneously.The sensor is fabricated by a polymer optical fiber(POF)with a side-polished spiral struc...The work describes a surface plasmon resonance(SPR)sensor that measures the liquid level and refractive index(RI)simultaneously.The sensor is fabricated by a polymer optical fiber(POF)with a side-polished spiral structure.The POF is wound around a plastic rod with the same pitch and polished into a series of separated side-polished areas to form the sensor probe.Afterwards,the polished surfaces are coated with a gold layer to construct the SPR sensor.The proposed sensor can provide multi-point liquid-level measurement besides RI sensing.The influences of structural parameters such as the bending radius,polishing depth,and pitch on the sensing performance are experimentally studied.The experimental results indicate that the RI could be determined by employing the SPR wavelength shift,and the RI sensitivity of 1862 nm/RIU within the 1.34–1.40 range is obtained.Moreover,the SPR peak’s depth variation can be utilized to monitor the liquid level,and the sensor can provide adjustable resolution and a measurement range for liquid level sensing.With its simple fabrication,low cost,and flexible sensing ability,this sensor probe is suitable for the usage in biochemical applications.展开更多
We proposed a fiber optic high temperature sensor based on the Mach-Zehnder interference(MZI)structure,which is composed of two lengths of multi-mode fibers(MMFs),a length of few-mode fiber(FMF)and two sections of sin...We proposed a fiber optic high temperature sensor based on the Mach-Zehnder interference(MZI)structure,which is composed of two lengths of multi-mode fibers(MMFs),a length of few-mode fiber(FMF)and two sections of single-mode fibers(SMFs).Firstly,the two sections of MMFs were spliced with two sections of SMFs.Then,the MMFs were fused to two ends of FMF to form a symmetrically structured fiber-optic MZI structure.In this structure,the MMF served as the optical mode field coupling element,and the cladding and core of the FMF are the interference arm and the reference arm of the MZI structure,respectively.We investigated the sensor's response characteristics of the temperature and strain.The experimental results indicate that the sensor is sensitive to temperature variation,and the temperature response sensitivity is up to 61.4 pm/℃ in the range of 40-250℃,while the sensor has weak strain sensitivity,its strain sensitivity is only-0.72 pm/μe in the strain range of 0-1400μe.Moreover,the sensor has good stability and repeatability.In brief,the proposed fiber optic high temperature sensor has good properties,such as high sensitivity,compact structure,good stability and repeatability,which can be used for monitoring the temperature of submerged oil electric pump units under oil wells.展开更多
Optical fiber sensor networks(OFSNs)provide powerful tools for large-scale buildings or long-distance sensing,and they can realize distributed or quasi-distributed measurement of temperature,strain,and other physical ...Optical fiber sensor networks(OFSNs)provide powerful tools for large-scale buildings or long-distance sensing,and they can realize distributed or quasi-distributed measurement of temperature,strain,and other physical quantities.This article provides some optical fiber sensor network technologies based on the white light interference technology.We discuss the key issues in the fiber white light interference network,including the topology structure of white light interferometric fiber sensor network,the node connection components,and evaluation of the maximum number of sensors in the network.A final comment about further development prospects of fiber sensor network is presented.展开更多
The femtosecond laser has emerged as a powerful tool for micro-and nanoscale device fabrication. Through nonlinear ionization processes, nanometer-sized material modifications can be inscribed in transparent materials...The femtosecond laser has emerged as a powerful tool for micro-and nanoscale device fabrication. Through nonlinear ionization processes, nanometer-sized material modifications can be inscribed in transparent materials for device fabrication. This paper describes femtosecond precision inscription of nanograting in silica fiber cores to form both distributed and point fiber sensors for sensing applications in extreme environmental conditions. Through the use of scanning electron microscope imaging and laser processing optimization,high-temperature stable, Type II femtosecond laser modifications were continuously inscribed,point by point, with only an insertion loss at 1 d B m~(-1) or 0.001 d B per point sensor device.High-temperature performance of fiber sensors was tested at 1000℃, which showed a temperature fluctuation of ±5.5℃ over 5 days. The low laser-induced insertion loss in optical fibers enabled the fabrication of a 1.4 m, radiation-resilient distributed fiber sensor. The in-pile testing of the distributed fiber sensor further showed that fiber sensors can execute stable and distributed temperature measurements in extreme radiation environments. Overall, this paper demonstrates that femtosecond-laser-fabricated fiber sensors are suitable measurement devices for applications in extreme environments.展开更多
Benefiting from the great advances of the femtosecond laser two-photon polymerization(TPP)technology,customized microcantilever probes can be accurately 3-dimensional(3D)manufactured at the nanoscale size and thus hav...Benefiting from the great advances of the femtosecond laser two-photon polymerization(TPP)technology,customized microcantilever probes can be accurately 3-dimensional(3D)manufactured at the nanoscale size and thus have exhibited considerable potentials in the fields of microforce,micro-vibration,and microforce sensors.In this work,a controllable microstructured cantilever probe on an optical fiber tip for microforce detection is demonstrated both theoretically and experimentally.The static performances of the probe are firstly investigated based on the finite element method(FEM),which provides the basis for the structural design.The proposed cantilever probe is then 3D printed by means of the TPP technology.The experimental results show that the elastic constant k of the proposed cantilever probe can be actively tuned from 2.46N/m to 62.35N/m.The force sensitivity is 2.5nm/μN,the Q-factor is 368.93,and the detection limit is 57.43nN.Moreover,the mechanical properties of the cantilever probe can be flexibly adjusted by the geometric configuration of the cantilever.Thus,it has an enormous potential for matching the mechanical properties of biological samples in the direct contact mode.展开更多
At present, the demand for perimeter security system is in-creasing greatly, especially for such system based on distribut-ed optical fiber sensing. This paper proposes a perimeter se-curity monitoring system based on...At present, the demand for perimeter security system is in-creasing greatly, especially for such system based on distribut-ed optical fiber sensing. This paper proposes a perimeter se-curity monitoring system based on phase-sensitive coherentoptical time domain reflectometry(Ф-COTDR) with the practi-cal pattern recognition function. We use fast Fourier trans-form(FFT) to exact features from intrusion events and a multi-class classification algorithm derived from support vector ma-chine(SVM) to work as a pattern recognition technique. Fivedifferent types of events are classified by using a classifica-tion algorithm based on SVM through a three-dimensional fea-ture vector. Moreover, the identification results of the patternrecognition system show that an identification accurate rate of92.62% on average can be achieved.展开更多
Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study pr...Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study presents a state-of-the-art review of the DFOS applications for monitoring and assessing the deformation behavior of typical tunnel infrastructure,including bored tunnels,conventional tunnels,as well as immersed and cut-and-cover tunnels.DFOS systems based on Brillouin and Rayleigh scattering principles are both considered.When implementing DFOS monitoring,the fiber optic cable can be primarily installed along transverse and longitudinal directions to(1)measure distributed strains by continuously adhering the fiber to the structure’s surface or embedding it in the lining,or(2)measure point displacements by spot-anchoring it on the lining surface.There are four critical aspects of DFOS monitoring,including proper selection of the sensing fiber,selection of the measuring principle for the specific application,design of an effective sensor layout,and establishment of robust field sensor instrumentation.These four issues are comprehensively discussed,and practical suggestions are provided for the implementation of DFOS in tunnel infrastructure monitoring.展开更多
The pandemic of respiratory diseases enlightened people that monitoring respiration has promising prospects in averting many fatalities by tracking the development of diseases.However,the response speed of current opt...The pandemic of respiratory diseases enlightened people that monitoring respiration has promising prospects in averting many fatalities by tracking the development of diseases.However,the response speed of current optical fiber sensors is still insufficient to meet the requirements of high-frequency respiratory detection during respiratory failure.Here,a scheme for a fast and stable tachypnea monitor is proposed utilizing a water-soluble C_(60)-Lys ion compound as functional material for the tracking of humidity change in the progression of breath.The polarization of C_(60)-Lys can be tuned by the ambient relative humidity change,and an apparent refractive index alteration can be detected due to the small size effect.In our experiments,C_(60)-Lys is conformally and uniformly deposited on the surface of a tilted fiber Bragg grating(TFBG)to fabricate an ultra-fast-response,high-sensitivity,and long-term stable optical fiber humidity sensor.A relative humidity(RH)detecting sensitivity of 0.080 dB/%RH and the equilibrium response time and recovery time of 1.85 s and 1.58 s are observed,respectively.Also,a linear relation is detected between the resonance intensity of the TFBG and the environment RH.In a practical breath monitoring experiment,the instantaneous response time and recovery time are measured as 40 ms and 41 ms,respectively,during a 1.5 Hz fast breath process.Furthermore,an excellent time stability and high repeatability are exhibited in experiments conducted over a range of 7 days.展开更多
In the aerospace field,for aerospace engines and other high-end manufacturing equipment working in extreme environments,like ultrahigh temperatures,high pressure,and high-speed airflow,in situ temperature measurement ...In the aerospace field,for aerospace engines and other high-end manufacturing equipment working in extreme environments,like ultrahigh temperatures,high pressure,and high-speed airflow,in situ temperature measurement is of great importance for improving the structure design and achieving the health monitoring and the fault diagnosis of critical parts.Optical fiber sensors have the advantages of small size,easy design,corrosion resistance,anti-electromagnetic interference,and the ability to achieve distributed or quasi-distributed sensing and have broad application prospects for temperature sensing in extreme environments.In this review,first,we introduce the current research status of fiber Bragg grating-type and Fabry–Perot interferometer-type high-temperature sensors.Then we review the optical fiber hightemperature sensor encapsulation techniques,including tubular encapsulation,substrate encapsulation,and metalembedded encapsulation,and discuss the extreme environmental adaptability of different encapsulation structures.Finally,the critical technological issues that need to be solved for the application of optical fiber sensors in extreme environments are discussed.展开更多
This paper proposes an optical fiber evanescent wave sensor for phase transition detection of organic compounds,which was validated using n-octadecane.The sensor is constructed by arc-discharge splicing single-mode fi...This paper proposes an optical fiber evanescent wave sensor for phase transition detection of organic compounds,which was validated using n-octadecane.The sensor is constructed by arc-discharge splicing single-mode fiber(SMF)into a waist-enlarged fusion taper(WEFT)structure using a fiber fusion splicer.When two WEFTs are connected in series,they form a Mach–Zehnder interferometer(MZI).Since n-octadecane has different refractive indices in its solid and liquid states during the phase change,the change in refractive index causes variation in the interference dips in the spectrum,enabling the distinction between the solid and liquid states.However,traditional wavelength and intensity tracking methods require precise numerical analysis,limiting their practical applications.Therefore,we propose using machine learning to assist the WEFT structure in phase change detection.During the heating and cooling processes,the K-means algorithm is first applied to classify the solid and liquid states,corresponding to the two phases of the transition.Subsequently,a Gaussian mixture model(GMM)is used for optimization,allowing for accurate differentiation between the liquid and solid states of n-octadecane.The results show that during the heating and cooling processes,after training on the spectral data,the average silhouette coefficients were 0.8619 and 0.8813,respectively,and the log-likelihood values were-21.8062 and-1.175.The sensor we propose has a simple structure and is easy to manufacture.Combined with machine learning algorithms,it holds great potential for application in the field of phase change energy storage.展开更多
Four sensing membranes based on fluorescence quenching were prepared by sol-gel method and CA membrane method, and the Ru(Ⅱ) complexes, Ru( bpy)3 Cl2 and Ru(phen)3 Cl2 , were used as the indicators . The results indi...Four sensing membranes based on fluorescence quenching were prepared by sol-gel method and CA membrane method, and the Ru(Ⅱ) complexes, Ru( bpy)3 Cl2 and Ru(phen)3 Cl2 , were used as the indicators . The results indicate that the volume fraction of oxygen o2 have a linear relationship in large scale with tan0/tanfor all of the sensing membranes. They have super properties such as excellent limit of detection ,fast response time and good reproducibility. The stability of the sensing membranes made by sol-gel method is better than those by CA membranes, but the uniformity of the latter is better than that of the former.展开更多
Modified sensing membranes based on fluorescence quenching were prepared by the sol-gel method,using formamide as the drying control chemical additive,tetraethoxysilane as the main material,Ru(phen) 3Cl 2 as the ind...Modified sensing membranes based on fluorescence quenching were prepared by the sol-gel method,using formamide as the drying control chemical additive,tetraethoxysilane as the main material,Ru(phen) 3Cl 2 as the indicator.The membrane with the optimum thickness of 20-50μm is uniform and crack-free,in which the indicator has a very small leaking rate.The membrane is immersed in water for 50h,the membrane sensing parameter M decreases by less than 5%.The fiber optic oxygen sensor with the sensing membrane has a detection limit of 5×10 -6M(ppm),a response time of less than 30s,excellent reproducibility and stability.展开更多
In this work the authors first summarily describe the main topics that were the subject of their post-graduate activity in fiber sensing at the Applied Optics Group of University of Kent in the late 1980s and early 19...In this work the authors first summarily describe the main topics that were the subject of their post-graduate activity in fiber sensing at the Applied Optics Group of University of Kent in the late 1980s and early 1990s. After their return to Porto, Portugal, the know-how acquired during their stay at Kent and the collaboration paths that followed between the University of Porto and University of Kent were instrumental in the start-up and progress of optical fiber sensing activity in Portugal. The main topics addressed in this field, the description of some of the relevant developments achieved in recent years, the present situation and the guidelines for the future research and development activity in Portugal in fiber sensing will be the core of this work.展开更多
The optical fiber based on silicon materials has a smaller thermal expansion coefficient, therefore it can be used for the preparation of sensor devices which are insensitive to temperature but sensitive to refracti...The optical fiber based on silicon materials has a smaller thermal expansion coefficient, therefore it can be used for the preparation of sensor devices which are insensitive to temperature but sensitive to refractive index, strain, stress, etc. For example, we can use optical fiber Fabry-Perot （F-P） sensor to achieve high sensitivity stress sensing. In this paper, we design an optical fiber F-P sensor with low cost and high sensitivity based on chemical etching method and analyze the stress sensing properties. Hydrofluoric acid is used to prepare the end face concave hole of the optical fiber first, and then the hollow struc-ture of the fiber F-P sensor is obtained by melting and discharge. This preparation method contributes greatly to enhancing the stress sensing properties and temperature insensitivity of the optical fiber device. The experimental results show that interference spectrum peak change is proportional to the stress change of optical fiber F-P sensor, stress sensitivity can reach 5. 2, and the cost is relatively low. Based on this,it has a certain application value in the stress sensing field.展开更多
Optical fiber interferometric sensors are of great importance in chemistry,biology,and medicine disciplines owing to high-sensitivity and high-quality factor.However,due to the limitation of free spectral range,the in...Optical fiber interferometric sensors are of great importance in chemistry,biology,and medicine disciplines owing to high-sensitivity and high-quality factor.However,due to the limitation of free spectral range,the inherent trade-off between wide measurement range and high sensitivity poses a persistent challenge in interference sensor development,which has fundamentally hindered their widespread adoption in precision measurement applications.In this work,a long short-term memory neural network is utilized in a Mach-Zehnder interference-based refractive index sensor to break the free spectral range limitation.Unique gating mechanism in long short-term memory neural network enables it to efficiently process long-term dependent sequence information,such as interference spectrum,avoiding the need for complex spectral signal analysis.A one-to-one mapping relationship is established between the interference spectrum and refractive index with root mean square error of 3.029×10^(−4)and a coefficient of determination of 0.99971.The measurement range is extended from a single free spectral range of 1.3333–1.3561 to approximately three free spectral ranges of 1.3333–1.3921 without sacrificing sensitivity.Moreover,a wider measurement range can be achieved with sufficient training data.This work successfully resolves the inherent contradiction between high sensitivity and wide dynamic measurement range in optical interference-based sensors,opening up a path for the next generation of intelligent sensing systems.展开更多
Optical fiber sensor network has attracted considerable research interests for geoscience applications.However,the sensor capacity and ultra-low frequency noise limits the sensing performance for geoscience data acqui...Optical fiber sensor network has attracted considerable research interests for geoscience applications.However,the sensor capacity and ultra-low frequency noise limits the sensing performance for geoscience data acquisition.To achieve a high-resolution and lager sensing capacity,a strain sensor network is proposed based on phase-sensitive op-tical time domain reflectometer(φ-OTDR)technology and special packaged fiber with scatter enhanced points(SEPs)ar-ray.Specifically,an extra identical fiber with SEPs array which is free of strain is used as the reference fiber,for com-pensating the ultra-low frequency noise in theφ-OTDR system induced by laser source frequency shift and environment temperature change.Moreover,a hysteresis operator based least square support vector machine(LS-SVM)model is in-troduced to reduce the compensation residual error generated from the thermal hysteresis nonlinearity between the sensing fiber and reference fiber.In the experiment,the strain sensor network possesses a sensing capacity with 55 sensor elements.The phase bias drift with frequency below 0.1 Hz is effectively compensated by LS-SVM based hyster-esis model,and the signal to noise ratio(SNR)of a strain vibration at 0.01 Hz greatly increases by 24 dB compared to that of the sensing fiber for direct compensation.The proposed strain sensor network proves a high dynamic resolution of 10.5 pε·Hz-1/2 above 10 Hz,and ultra-low frequency sensing resolution of 166 pεat 0.001 Hz.It is the first reported a large sensing capacity strain sensor network with sub-nεsensing resolution in mHz frequency range,to the best of our knowledge.展开更多
A refractive index(RI)sensor based on perfluorinated plastic optical fiber(PF-POF)is introduced in this paper.The PF-POF as multi-mode fiber was side-polished(SP)to form a macro-bending single-mode-multimode-single-mo...A refractive index(RI)sensor based on perfluorinated plastic optical fiber(PF-POF)is introduced in this paper.The PF-POF as multi-mode fiber was side-polished(SP)to form a macro-bending single-mode-multimode-single-mode(SMS)structure.Both ends of the sensor were closely connected to single-mode quartz optical fiber(SMF).The spectral char-acteristics of the sensor are measured,analyzed and discussed.The results show that when the length of PF-POF is 8 cm,the macro-bending radius is 3 cm,and the SP-depth is 20μm.The intensity sensitivity reaches−219.504 dBm/RIU in the range of RI=1.330~1.356.A reference is provided for the application of PF-POF in RI sensor in the future.The sensor is featured with low-cost,good flexibility and high efficiency.展开更多
文摘Soft polymer optical fiber(SPOF)has shown great potential in optical-based wearable and implantable biosensors due to its excellent mechanical properties and optical guiding characteristics.However,the multimodality characteristics of SPOF limit their integration with traditional fiber optic sensors.This article introduces for the first time a flexible fiber optic vibration sensor based on laser interference technology,which can be applied to vibration measurement under high stretch conditions.This sensor utilizes elastic optical fibers made of polydimethylsiloxane(PDMS)as sensing elements,combined with phase generating carrier technology,to achieve vibration measurement at 50−260 Hz within the stretch range of 0−42%.
基金the financial supports of the National Natural Science Foundation of China(No.52372200)a project supported by the State Key Laboratory of Mechanics and Control for Aerospace Structures(No.MCAS-S-0324G01)。
文摘Battery safety has emerged as a critical challenge for achieving carbon neutrality,driven by the increasing frequency of thermal runaway incidents in electric vehicles(EVs)and stationary energy storage systems(ESSs).Conventional battery monitoring technologies struggle to track multiple physicochemical parameters in real time,hindering early hazard detection.Embedded optical fiber sensors have gained prominence as a transformative solution for next-generation smart battery sensing,owing to their micrometer size,multiplexing capability,and electromagnetic immunity.However,comprehensive reviews focusing on their advancements in operando multi-parameter monitoring remain scarce,despite their critical importance for ensuring battery safety.To address this gap,this review first introduces a classification and the fundamental principles of advanced battery-oriented optical fiber sensors.Subsequently,it summarizes recent developments in single-parameter battery monitoring using optical fiber sensors.Building on this foundation,this review presents the first comprehensive analysis of multifunctional optical fiber sensing platforms capable of simultaneously tracking temperature,strain,pressure,refractive index,and monitoring battery aging.Targeted strategies are proposed to facilitate the practical development of this technology,including optimization of sensor integration techniques,minimizing sensor invasiveness,resolving the cross-sensitivity of fiber Bragg grating(FBG)through structural innovation,enhancing techno-economics,and combining with artificial intelligence(AI).By aligning academic research with industry requirements,this review provides a methodological roadmap for developing robust optical sensing systems to ensure battery safety in decarbonization-driven applications.
基金financial supports from Ministry of Science and Technology of the People’s Republic of China under Grant(No.2022YFC2203904)in part by Open Projects Foundation under Grant of State Key Laboratory of Optical Fiber and Cable Manufacture Technology(YOFC)(No.SKLD2306).
文摘Time division multiplexing(TDM)architecture is an important approach to creating sensor arrays for massive scale monitoring.But it is paradoxical for the TDM interferometric sensor array to keep a short delay fiber for high sensing resolution and meanwhile use low sampling rate for practical applications.In this paper,a phase matching sampling(PMS)paradigm is proposed to address the above contradiction.By matching the phase of the sampling clock with the delay fiber length,combining with multiple-pulses sampling strategy,the proposed PMS method can avoid collecting the redundant information,facilitating the decreasing of sampling rate as well as delay fiber length of the TDM sensing system.The proof-of-concept experiments on an 8-channel TDM interferometric system demonstrate that when the sampling rate is fixed at 20 MS/s,by applying the PMS algorithm,the delay fiber length can be shortened from 100 m to 1 m,compared with applying the conventional sampling method.It reduced the phase noise of the system by a factor of 10 at 1 mHz and by a factor of 50 at 1 Hz.The PMS algorithm for greatly reducing the sampling rate is expected to fuel the TDM interferometric sensor arrays for many applications.
基金supported by the Guangxi Natural Science Foundation,China(Grant Nos.2023GXNSFDA026040 and ZY23055018)National Natural Science Foundation of China(Grant Nos.62365003,62364006,and U23A20282)+2 种基金the Fonds de la Recherche Scientifique under the Postdoctoral Researcher Grant(Chargéde Recherches)Belgium to Xuehao HUthe Innovation Project of Guilin University of Electronic Technology Graduate Education,China(Grant No.2024YCXS202).
文摘The work describes a surface plasmon resonance(SPR)sensor that measures the liquid level and refractive index(RI)simultaneously.The sensor is fabricated by a polymer optical fiber(POF)with a side-polished spiral structure.The POF is wound around a plastic rod with the same pitch and polished into a series of separated side-polished areas to form the sensor probe.Afterwards,the polished surfaces are coated with a gold layer to construct the SPR sensor.The proposed sensor can provide multi-point liquid-level measurement besides RI sensing.The influences of structural parameters such as the bending radius,polishing depth,and pitch on the sensing performance are experimentally studied.The experimental results indicate that the RI could be determined by employing the SPR wavelength shift,and the RI sensitivity of 1862 nm/RIU within the 1.34–1.40 range is obtained.Moreover,the SPR peak’s depth variation can be utilized to monitor the liquid level,and the sensor can provide adjustable resolution and a measurement range for liquid level sensing.With its simple fabrication,low cost,and flexible sensing ability,this sensor probe is suitable for the usage in biochemical applications.
基金supported by the Scientific Research Program Funded by Shaanxi Provincial Education Department (No.15JK1573)the Postgraduate Innovation and Practice Ability Development Fund of Xi’an Shiyou University (No.YCS21211084)。
文摘We proposed a fiber optic high temperature sensor based on the Mach-Zehnder interference(MZI)structure,which is composed of two lengths of multi-mode fibers(MMFs),a length of few-mode fiber(FMF)and two sections of single-mode fibers(SMFs).Firstly,the two sections of MMFs were spliced with two sections of SMFs.Then,the MMFs were fused to two ends of FMF to form a symmetrically structured fiber-optic MZI structure.In this structure,the MMF served as the optical mode field coupling element,and the cladding and core of the FMF are the interference arm and the reference arm of the MZI structure,respectively.We investigated the sensor's response characteristics of the temperature and strain.The experimental results indicate that the sensor is sensitive to temperature variation,and the temperature response sensitivity is up to 61.4 pm/℃ in the range of 40-250℃,while the sensor has weak strain sensitivity,its strain sensitivity is only-0.72 pm/μe in the strain range of 0-1400μe.Moreover,the sensor has good stability and repeatability.In brief,the proposed fiber optic high temperature sensor has good properties,such as high sensitivity,compact structure,good stability and repeatability,which can be used for monitoring the temperature of submerged oil electric pump units under oil wells.
文摘Optical fiber sensor networks(OFSNs)provide powerful tools for large-scale buildings or long-distance sensing,and they can realize distributed or quasi-distributed measurement of temperature,strain,and other physical quantities.This article provides some optical fiber sensor network technologies based on the white light interference technology.We discuss the key issues in the fiber white light interference network,including the topology structure of white light interferometric fiber sensor network,the node connection components,and evaluation of the maximum number of sensors in the network.A final comment about further development prospects of fiber sensor network is presented.
基金supported in part through Department of Energy Grants DE-NE0008686 and DE-FE00028992the NEET ASI program under DOE Idaho Operations Office Contract DE-AC07-05ID14517。
文摘The femtosecond laser has emerged as a powerful tool for micro-and nanoscale device fabrication. Through nonlinear ionization processes, nanometer-sized material modifications can be inscribed in transparent materials for device fabrication. This paper describes femtosecond precision inscription of nanograting in silica fiber cores to form both distributed and point fiber sensors for sensing applications in extreme environmental conditions. Through the use of scanning electron microscope imaging and laser processing optimization,high-temperature stable, Type II femtosecond laser modifications were continuously inscribed,point by point, with only an insertion loss at 1 d B m~(-1) or 0.001 d B per point sensor device.High-temperature performance of fiber sensors was tested at 1000℃, which showed a temperature fluctuation of ±5.5℃ over 5 days. The low laser-induced insertion loss in optical fibers enabled the fabrication of a 1.4 m, radiation-resilient distributed fiber sensor. The in-pile testing of the distributed fiber sensor further showed that fiber sensors can execute stable and distributed temperature measurements in extreme radiation environments. Overall, this paper demonstrates that femtosecond-laser-fabricated fiber sensors are suitable measurement devices for applications in extreme environments.
基金supported by the Shenzhen Science and Technology Program (Grant No.RCYX20200714114524139)Shenzhen Key Laboratory of Ultrafast Laser Micro/Nano Manufacturing (Grant No.ZDSYS20220606100405013)+2 种基金Natural Science Foundation of GuangdongProvince (Grant Nos.2022B1515120061 and 2022A1515110971)National Natural Science Foundation of China (Grant Nos.62122057,62075136,62105217,and 62305223)China Postdoctoral Science Foundation (Grant No.2022M722173).
文摘Benefiting from the great advances of the femtosecond laser two-photon polymerization(TPP)technology,customized microcantilever probes can be accurately 3-dimensional(3D)manufactured at the nanoscale size and thus have exhibited considerable potentials in the fields of microforce,micro-vibration,and microforce sensors.In this work,a controllable microstructured cantilever probe on an optical fiber tip for microforce detection is demonstrated both theoretically and experimentally.The static performances of the probe are firstly investigated based on the finite element method(FEM),which provides the basis for the structural design.The proposed cantilever probe is then 3D printed by means of the TPP technology.The experimental results show that the elastic constant k of the proposed cantilever probe can be actively tuned from 2.46N/m to 62.35N/m.The force sensitivity is 2.5nm/μN,the Q-factor is 368.93,and the detection limit is 57.43nN.Moreover,the mechanical properties of the cantilever probe can be flexibly adjusted by the geometric configuration of the cantilever.Thus,it has an enormous potential for matching the mechanical properties of biological samples in the direct contact mode.
文摘At present, the demand for perimeter security system is in-creasing greatly, especially for such system based on distribut-ed optical fiber sensing. This paper proposes a perimeter se-curity monitoring system based on phase-sensitive coherentoptical time domain reflectometry(Ф-COTDR) with the practi-cal pattern recognition function. We use fast Fourier trans-form(FFT) to exact features from intrusion events and a multi-class classification algorithm derived from support vector ma-chine(SVM) to work as a pattern recognition technique. Fivedifferent types of events are classified by using a classifica-tion algorithm based on SVM through a three-dimensional fea-ture vector. Moreover, the identification results of the patternrecognition system show that an identification accurate rate of92.62% on average can be achieved.
基金funding support from Rijkswaterstaat,the Netherlands,and European Union’s Horizon 2020 Research and Innovation Programme(Project SAFE-10-T under Grant No.723254)China Scholarship Council,and National Natural Science Foundation of China(Grant No.42225702).
文摘Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study presents a state-of-the-art review of the DFOS applications for monitoring and assessing the deformation behavior of typical tunnel infrastructure,including bored tunnels,conventional tunnels,as well as immersed and cut-and-cover tunnels.DFOS systems based on Brillouin and Rayleigh scattering principles are both considered.When implementing DFOS monitoring,the fiber optic cable can be primarily installed along transverse and longitudinal directions to(1)measure distributed strains by continuously adhering the fiber to the structure’s surface or embedding it in the lining,or(2)measure point displacements by spot-anchoring it on the lining surface.There are four critical aspects of DFOS monitoring,including proper selection of the sensing fiber,selection of the measuring principle for the specific application,design of an effective sensor layout,and establishment of robust field sensor instrumentation.These four issues are comprehensively discussed,and practical suggestions are provided for the implementation of DFOS in tunnel infrastructure monitoring.
基金supported by the National Natural Science Foundation of China(Nos.12274386 and 52002365)Zhejiang Provincial Natural Science Foundation of China(Nos.LQ23F050006,LY21F050006,and LQ21E020005)+1 种基金Key R&D Project of Zhejiang Province(No.2021C01179)National Key R&D Program of China(No.2021YFF0600203)。
文摘The pandemic of respiratory diseases enlightened people that monitoring respiration has promising prospects in averting many fatalities by tracking the development of diseases.However,the response speed of current optical fiber sensors is still insufficient to meet the requirements of high-frequency respiratory detection during respiratory failure.Here,a scheme for a fast and stable tachypnea monitor is proposed utilizing a water-soluble C_(60)-Lys ion compound as functional material for the tracking of humidity change in the progression of breath.The polarization of C_(60)-Lys can be tuned by the ambient relative humidity change,and an apparent refractive index alteration can be detected due to the small size effect.In our experiments,C_(60)-Lys is conformally and uniformly deposited on the surface of a tilted fiber Bragg grating(TFBG)to fabricate an ultra-fast-response,high-sensitivity,and long-term stable optical fiber humidity sensor.A relative humidity(RH)detecting sensitivity of 0.080 dB/%RH and the equilibrium response time and recovery time of 1.85 s and 1.58 s are observed,respectively.Also,a linear relation is detected between the resonance intensity of the TFBG and the environment RH.In a practical breath monitoring experiment,the instantaneous response time and recovery time are measured as 40 ms and 41 ms,respectively,during a 1.5 Hz fast breath process.Furthermore,an excellent time stability and high repeatability are exhibited in experiments conducted over a range of 7 days.
基金supported by the National Natural Science Foundation of China(No.62275269)National Key Research and Development Program of China(No.2022YFF0706005)+3 种基金China Guangdong Guangxi Joint Science Key Foundation(No.2021GXNSFDA076001)Guangxi Major Projects of ScienceandTechnology(No.2020AA21077007)Interdisciplinary Scientific Research Foundation of Guangxi University(No.2022JCC014)China Scholarship Council(No.201903170207)。
文摘In the aerospace field,for aerospace engines and other high-end manufacturing equipment working in extreme environments,like ultrahigh temperatures,high pressure,and high-speed airflow,in situ temperature measurement is of great importance for improving the structure design and achieving the health monitoring and the fault diagnosis of critical parts.Optical fiber sensors have the advantages of small size,easy design,corrosion resistance,anti-electromagnetic interference,and the ability to achieve distributed or quasi-distributed sensing and have broad application prospects for temperature sensing in extreme environments.In this review,first,we introduce the current research status of fiber Bragg grating-type and Fabry–Perot interferometer-type high-temperature sensors.Then we review the optical fiber hightemperature sensor encapsulation techniques,including tubular encapsulation,substrate encapsulation,and metalembedded encapsulation,and discuss the extreme environmental adaptability of different encapsulation structures.Finally,the critical technological issues that need to be solved for the application of optical fiber sensors in extreme environments are discussed.
文摘This paper proposes an optical fiber evanescent wave sensor for phase transition detection of organic compounds,which was validated using n-octadecane.The sensor is constructed by arc-discharge splicing single-mode fiber(SMF)into a waist-enlarged fusion taper(WEFT)structure using a fiber fusion splicer.When two WEFTs are connected in series,they form a Mach–Zehnder interferometer(MZI).Since n-octadecane has different refractive indices in its solid and liquid states during the phase change,the change in refractive index causes variation in the interference dips in the spectrum,enabling the distinction between the solid and liquid states.However,traditional wavelength and intensity tracking methods require precise numerical analysis,limiting their practical applications.Therefore,we propose using machine learning to assist the WEFT structure in phase change detection.During the heating and cooling processes,the K-means algorithm is first applied to classify the solid and liquid states,corresponding to the two phases of the transition.Subsequently,a Gaussian mixture model(GMM)is used for optimization,allowing for accurate differentiation between the liquid and solid states of n-octadecane.The results show that during the heating and cooling processes,after training on the spectral data,the average silhouette coefficients were 0.8619 and 0.8813,respectively,and the log-likelihood values were-21.8062 and-1.175.The sensor we propose has a simple structure and is easy to manufacture.Combined with machine learning algorithms,it holds great potential for application in the field of phase change energy storage.
基金Funded by The Key Scientific Project Foundation of Hubei Province (No.2001AA101A02) and Natural Science Foundation of Hubei Province (No.2001ABB074)
文摘Four sensing membranes based on fluorescence quenching were prepared by sol-gel method and CA membrane method, and the Ru(Ⅱ) complexes, Ru( bpy)3 Cl2 and Ru(phen)3 Cl2 , were used as the indicators . The results indicate that the volume fraction of oxygen o2 have a linear relationship in large scale with tan0/tanfor all of the sensing membranes. They have super properties such as excellent limit of detection ,fast response time and good reproducibility. The stability of the sensing membranes made by sol-gel method is better than those by CA membranes, but the uniformity of the latter is better than that of the former.
文摘Modified sensing membranes based on fluorescence quenching were prepared by the sol-gel method,using formamide as the drying control chemical additive,tetraethoxysilane as the main material,Ru(phen) 3Cl 2 as the indicator.The membrane with the optimum thickness of 20-50μm is uniform and crack-free,in which the indicator has a very small leaking rate.The membrane is immersed in water for 50h,the membrane sensing parameter M decreases by less than 5%.The fiber optic oxygen sensor with the sensing membrane has a detection limit of 5×10 -6M(ppm),a response time of less than 30s,excellent reproducibility and stability.
文摘In this work the authors first summarily describe the main topics that were the subject of their post-graduate activity in fiber sensing at the Applied Optics Group of University of Kent in the late 1980s and early 1990s. After their return to Porto, Portugal, the know-how acquired during their stay at Kent and the collaboration paths that followed between the University of Porto and University of Kent were instrumental in the start-up and progress of optical fiber sensing activity in Portugal. The main topics addressed in this field, the description of some of the relevant developments achieved in recent years, the present situation and the guidelines for the future research and development activity in Portugal in fiber sensing will be the core of this work.
基金National Natural Science Foundation of China(No.61405127)Shanxi Province Science Foundation for Youths(No.2014021023-1)+1 种基金Scientific and Technologial Innovation Programs of Higher Education Institutions in ShanxiProgram for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province
文摘The optical fiber based on silicon materials has a smaller thermal expansion coefficient, therefore it can be used for the preparation of sensor devices which are insensitive to temperature but sensitive to refractive index, strain, stress, etc. For example, we can use optical fiber Fabry-Perot （F-P） sensor to achieve high sensitivity stress sensing. In this paper, we design an optical fiber F-P sensor with low cost and high sensitivity based on chemical etching method and analyze the stress sensing properties. Hydrofluoric acid is used to prepare the end face concave hole of the optical fiber first, and then the hollow struc-ture of the fiber F-P sensor is obtained by melting and discharge. This preparation method contributes greatly to enhancing the stress sensing properties and temperature insensitivity of the optical fiber device. The experimental results show that interference spectrum peak change is proportional to the stress change of optical fiber F-P sensor, stress sensitivity can reach 5. 2, and the cost is relatively low. Based on this,it has a certain application value in the stress sensing field.
基金supported by the National Natural Science Foundation of China(Grant No.12074331)Natural Science Foundation of Hebei Province of China(Grant No.F2021203112)Open project of Hebei Key Laboratory of Advanced Laser Technology and Equipment(Grant No.HBKL-ALTE2025006).
文摘Optical fiber interferometric sensors are of great importance in chemistry,biology,and medicine disciplines owing to high-sensitivity and high-quality factor.However,due to the limitation of free spectral range,the inherent trade-off between wide measurement range and high sensitivity poses a persistent challenge in interference sensor development,which has fundamentally hindered their widespread adoption in precision measurement applications.In this work,a long short-term memory neural network is utilized in a Mach-Zehnder interference-based refractive index sensor to break the free spectral range limitation.Unique gating mechanism in long short-term memory neural network enables it to efficiently process long-term dependent sequence information,such as interference spectrum,avoiding the need for complex spectral signal analysis.A one-to-one mapping relationship is established between the interference spectrum and refractive index with root mean square error of 3.029×10^(−4)and a coefficient of determination of 0.99971.The measurement range is extended from a single free spectral range of 1.3333–1.3561 to approximately three free spectral ranges of 1.3333–1.3921 without sacrificing sensitivity.Moreover,a wider measurement range can be achieved with sufficient training data.This work successfully resolves the inherent contradiction between high sensitivity and wide dynamic measurement range in optical interference-based sensors,opening up a path for the next generation of intelligent sensing systems.
基金financial supports from the National Natural Science Foundation of China(NSFC)(No.61922033&61775072)Major Technology Innovation of Hubei Province(2019AAA053)+1 种基金Foundation for Innovative Research Groups of Hubei Province of China(2018CFA004)Innovation Fund of WNLO。
文摘Optical fiber sensor network has attracted considerable research interests for geoscience applications.However,the sensor capacity and ultra-low frequency noise limits the sensing performance for geoscience data acquisition.To achieve a high-resolution and lager sensing capacity,a strain sensor network is proposed based on phase-sensitive op-tical time domain reflectometer(φ-OTDR)technology and special packaged fiber with scatter enhanced points(SEPs)ar-ray.Specifically,an extra identical fiber with SEPs array which is free of strain is used as the reference fiber,for com-pensating the ultra-low frequency noise in theφ-OTDR system induced by laser source frequency shift and environment temperature change.Moreover,a hysteresis operator based least square support vector machine(LS-SVM)model is in-troduced to reduce the compensation residual error generated from the thermal hysteresis nonlinearity between the sensing fiber and reference fiber.In the experiment,the strain sensor network possesses a sensing capacity with 55 sensor elements.The phase bias drift with frequency below 0.1 Hz is effectively compensated by LS-SVM based hyster-esis model,and the signal to noise ratio(SNR)of a strain vibration at 0.01 Hz greatly increases by 24 dB compared to that of the sensing fiber for direct compensation.The proposed strain sensor network proves a high dynamic resolution of 10.5 pε·Hz-1/2 above 10 Hz,and ultra-low frequency sensing resolution of 166 pεat 0.001 Hz.It is the first reported a large sensing capacity strain sensor network with sub-nεsensing resolution in mHz frequency range,to the best of our knowledge.
基金supports in part by from the National key re-search and development plan of China(No.2016YFC0401902)in part by the National Natural Science Foundation of China(No.U1833104,No.61775163,No.61735011,No.61675152 and No.61405139).
文摘A refractive index(RI)sensor based on perfluorinated plastic optical fiber(PF-POF)is introduced in this paper.The PF-POF as multi-mode fiber was side-polished(SP)to form a macro-bending single-mode-multimode-single-mode(SMS)structure.Both ends of the sensor were closely connected to single-mode quartz optical fiber(SMF).The spectral char-acteristics of the sensor are measured,analyzed and discussed.The results show that when the length of PF-POF is 8 cm,the macro-bending radius is 3 cm,and the SP-depth is 20μm.The intensity sensitivity reaches−219.504 dBm/RIU in the range of RI=1.330~1.356.A reference is provided for the application of PF-POF in RI sensor in the future.The sensor is featured with low-cost,good flexibility and high efficiency.
