A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of...A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of about 257.2 rad·s2/m and a resolution of 4.2×10-5 m/s2 for monitoring acceleration.Experimental results show that the phase-shift changes with the acceleration linearly.展开更多
Through analyzing theoretically the temperature effect of the optical-fiber Raman backscattering,a distributed temperature sensor is designed based on the single-mode fiber. Demodulation methods of temperature transdu...Through analyzing theoretically the temperature effect of the optical-fiber Raman backscattering,a distributed temperature sensor is designed based on the single-mode fiber. Demodulation methods of temperature transduction are compared,and then the demodulation method using the ratio of the anti-Stokes and the Stokes Raman backscattering intensity is adopted. Both the hardware composition and the software realization of the system are introduced in detail. The experiment shows that the distinguishing ability of the temperature and that of the space are 1℃ and 2m,respectively,and that the system response time is about 180 s with a sensing range of 5km and with a temperature measurement range of 0-100℃.展开更多
We propose the trench-assisted multimode fiber(TA-OM4)as a novel sensing fiber in forward Brillouin scattering(FBS)-based temperature sensor,due to its higher temperature sensitivity,better bending resistance and lowe...We propose the trench-assisted multimode fiber(TA-OM4)as a novel sensing fiber in forward Brillouin scattering(FBS)-based temperature sensor,due to its higher temperature sensitivity,better bending resistance and lower propagation loss,compared with the single mode fiber(SMF)and other sensing fibers.The FBS effect and acousto-optic interaction in TA-OM4 are the first time to be demonstrated and characterized at 1550 nm theoretically and experimentally.A 2.0 km long TA-OM4 is put into an oven to measure its temperature sensitivity,which can reach up to 80.3 kHz/℃,exceeding 53%of SMF(52.4 kHz/℃).The simulated and experimental results verify that the TA-OM4 may be a good candidate as the sensing fiber for the FBS-based temperature sensor.展开更多
A kind of fiber Bragg grating pressure sensor based on corrugated diaphragm is proposed. The relationship between the central wavelength of reflective wave of FBG and pressure is given, and the expression of the press...A kind of fiber Bragg grating pressure sensor based on corrugated diaphragm is proposed. The relationship between the central wavelength of reflective wave of FBG and pressure is given, and the expression of the pressure sensitivity coefficient is also given. Within the range from 0 MPa to 0.3 MPa, the experimental pressure sensitivity is 7.83 nm/MPa, which is 2 610 times than that of the bare fiber grating. The experimental results agree with the theoretical analysis. It is indicated that the expected pressure sensitivity of the sensor can be obtained by optimizing the size and mechanical parameters of the corrugated diaphragm.展开更多
A novel method of correlation function for analyzing cross-sensitivity between strain and temperature is reported for the first time in this paper. Using the new method,the correlative characteristics between strain a...A novel method of correlation function for analyzing cross-sensitivity between strain and temperature is reported for the first time in this paper. Using the new method,the correlative characteristics between strain and temperature of fiber Bragg grating sensors are studied both theoretically and experimentally The experimental results accord with the theoretical calculations.展开更多
The combination of fiber optics with nano-structure technologies and sensitive thin films offers great potential for the realization of novel sensor concepts. Miniatured optical fiber sensors with thin films as sensit...The combination of fiber optics with nano-structure technologies and sensitive thin films offers great potential for the realization of novel sensor concepts. Miniatured optical fiber sensors with thin films as sensitive elements could open new fields for optical fiber sensor applications. Thin films work as sensitive elements and transducer to get response and feedback from environments, in which optical fibers are employed to work as signal carrier. This article presents some research work conducted at the National Engineering Laboratory for Optical Fiber Sensing Technologies in recent years. Concrete examples are： Pd/WO3 co-sputtered coating as sensing material for optical hydrogen sensors shows robust mechanical stability and meanwhile good sensing performance; TbDyFe magnetostrictive coating directly deposited on fiber Bragg grating （FBG） demonstrates its possibility of miniature optical magnetic field/current sensors, and 40-pm shift of the FBG wavelength happens at a magnetic field order of 50 mT.展开更多
In this paper, the most recent progress as well as challenges of distributed optical fiber sensing （DOFS） in industrial applications is discussed. Compared to the vast market of sensors used to measure strain or tem...In this paper, the most recent progress as well as challenges of distributed optical fiber sensing （DOFS） in industrial applications is discussed. Compared to the vast market of sensors used to measure strain or temperature, the success of distributed optical fiber sensing （DOFS） at the industrial level is very limited, at best. One of the reasons for this lack of the wider acceptance is the mismatch between the commercially available systems and actual industrial requirements, especially for the spatial resolution and precision. These requirements are organized and clarified in the paper. It also describes the hybrid Brillouin-Rayleigh system, which exhibits capabilities surpassing those of strain gauges. The principles of the system are illustrated considering the fiber calibration methodology. Formulas required for determining strain, temperature, and hydro-pressure are derived and discussed. Finally, the examples of applications are presented.展开更多
The key factor of the sensitivity in the FBG-based pH sensor is analyzed in detail. A multi-thin-layer structure of the gel coated cover was proposed and implemented with a special process. The sensors with the coated...The key factor of the sensitivity in the FBG-based pH sensor is analyzed in detail. A multi-thin-layer structure of the gel coated cover was proposed and implemented with a special process. The sensors with the coated thickness of 420 ~m, 500 ~m, and 580 ~m were built up, respectively. The corresponding spectral shifts of 0.08nm, 0.13nm, and 0.22nm were detected when the pH sensors were soaked in the pH value of 3-9. Meanwhile, the sensor with the gel layer thickness of 580 ~tm was measured in the optimum measurement time period with the pH value changing from 3-12, in which the detected sensitivity of 52pm/pH was achieved in the pH range of 6-12.展开更多
This article describes in detail a technique for model!ng cavity optomechanical field sensors. A magnetic or electric field induces a spatially varying stress across the sensor, which then induces a force on mechanica...This article describes in detail a technique for model!ng cavity optomechanical field sensors. A magnetic or electric field induces a spatially varying stress across the sensor, which then induces a force on mechanical eigenmodes of the system. The force on each oscillator can then be determined from an overlap integral between magnetostrictive stress and the corresponding eigenmode, with the optomechanical coupling strength determining the ultimate resolution with which this force can be detected. Furthermore, an optomechanical magnetic field sensor is compared to other magnetic field sensors in terms of sensitivity and potential for miniaturization. It is shown that an optomechanical sensor can potentially outperform state-of-the-art magnetometers of similar size, in particular other sensors based on a magnetostrictive mechanism.展开更多
A fiber Bragg grating strain sensor,whose reflection bandwidth is insensitive to temperature,is presented.The cross-sec-tional area is designed to change linearly.Under axial stress,there is a linear relationship betw...A fiber Bragg grating strain sensor,whose reflection bandwidth is insensitive to temperature,is presented.The cross-sec-tional area is designed to change linearly.Under axial stress,there is a linear relationship between stress and average strain.Experimental results show that when temperature increases,reflection center wavelength shifts to longer wavelength,and there is a good linear relationship between center wavelength and temperature.When stress increases,reflection center wavelength shifts to longer wavelength,and reflection bandwidth increases.There are good linear relationships between reflection center wavelength and stress as well as reflection bandwidth and stress.展开更多
In this paper, a novel liquid refractive index （R/） sensor based on fused tapered photonic crystal fiber （PCF） is proposed. It is fabricated by fusing and tapering a section of PCF which is spliced with two single...In this paper, a novel liquid refractive index （R/） sensor based on fused tapered photonic crystal fiber （PCF） is proposed. It is fabricated by fusing and tapering a section of PCF which is spliced with two single-mode fibers （SMFs）. Due to the fused biconical taper method, the sensor becomes longer and thinner, to make the change of the outside RI has more direct effects on the internal optical field of the PCF, which finally enhances the sensitivity of this sensor. Experimental results show that the transmission spectra of the sensor are red-shifted obviously with the increase of RI. The longer the tapered region of the sensor, the higher the sensitivity is. This sensor has the advantages of simple structure, easy fabri- cation, high performance and so on, so it has potential applications in RI measurement.展开更多
A highly sensitive and selective two-photon sensing scheme for detection of cartap was developed by using Au@Ag bimetallic core-shell nanoparticles.Cartap was found to induce the aggregation of Au@Ag nanoparticles and...A highly sensitive and selective two-photon sensing scheme for detection of cartap was developed by using Au@Ag bimetallic core-shell nanoparticles.Cartap was found to induce the aggregation of Au@Ag nanoparticles and up to 700-fold enhancement in two-photon photoluminescence.Huge enhancement in two-photon photoluminescence allows achieving a detection limit of as low as 0.0062 mg/kg,which is better than the conventional colorimetric methods.This two-photon sensing scheme has a broad dynamic range and displays excellent selectivity in detection of cartap against over other ten kinds of commonly used insecticides.展开更多
An index guiding photonic crystal fiber used in gas sensing applications is presented. The dependency of the confinement loss and relative sensitivity on the fiber parameters and wavelength is numerically investigated...An index guiding photonic crystal fiber used in gas sensing applications is presented. The dependency of the confinement loss and relative sensitivity on the fiber parameters and wavelength is numerically investigated by using the full-vectorial finite element method （FEM）. The simulations showed that the gas sensing sensitivity increased with an increase in the core diameter and a decrease in the distance between centers of two adjacent holes. Increasing the hole size of two outer cladding rings, this structure simultaneously showed up to 10% improved sensitivity, and the confinement loss reached 6x 10-4 times less than that of the prior sensor at the wavelength of 1.5 μm. This proved the ability of this fiber used in gas and chemicals sensing applications.展开更多
基金supported by the Science Fund for Young Scholars of Heilongjiang University,China(No.QL200901)
文摘A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of about 257.2 rad·s2/m and a resolution of 4.2×10-5 m/s2 for monitoring acceleration.Experimental results show that the phase-shift changes with the acceleration linearly.
基金Shandong Province Natural Science Foundation (No.Z2006G06)The Excellent Youth Scientist Award Foundation of Shandong Province (No.2006 BS 01001)
文摘Through analyzing theoretically the temperature effect of the optical-fiber Raman backscattering,a distributed temperature sensor is designed based on the single-mode fiber. Demodulation methods of temperature transduction are compared,and then the demodulation method using the ratio of the anti-Stokes and the Stokes Raman backscattering intensity is adopted. Both the hardware composition and the software realization of the system are introduced in detail. The experiment shows that the distinguishing ability of the temperature and that of the space are 1℃ and 2m,respectively,and that the system response time is about 180 s with a sensing range of 5km and with a temperature measurement range of 0-100℃.
基金supported in part by the National Natural Foundation of China(Nos. 61875086, 61377086)the Aerospace Science Foundation of China (No.2016ZD52042)Nanjing University of Aeronautics and Astronautics Ph. D. short-term visiting scholar project (No.190901DF08)
文摘We propose the trench-assisted multimode fiber(TA-OM4)as a novel sensing fiber in forward Brillouin scattering(FBS)-based temperature sensor,due to its higher temperature sensitivity,better bending resistance and lower propagation loss,compared with the single mode fiber(SMF)and other sensing fibers.The FBS effect and acousto-optic interaction in TA-OM4 are the first time to be demonstrated and characterized at 1550 nm theoretically and experimentally.A 2.0 km long TA-OM4 is put into an oven to measure its temperature sensitivity,which can reach up to 80.3 kHz/℃,exceeding 53%of SMF(52.4 kHz/℃).The simulated and experimental results verify that the TA-OM4 may be a good candidate as the sensing fiber for the FBS-based temperature sensor.
文摘A kind of fiber Bragg grating pressure sensor based on corrugated diaphragm is proposed. The relationship between the central wavelength of reflective wave of FBG and pressure is given, and the expression of the pressure sensitivity coefficient is also given. Within the range from 0 MPa to 0.3 MPa, the experimental pressure sensitivity is 7.83 nm/MPa, which is 2 610 times than that of the bare fiber grating. The experimental results agree with the theoretical analysis. It is indicated that the expected pressure sensitivity of the sensor can be obtained by optimizing the size and mechanical parameters of the corrugated diaphragm.
基金This work is supported by the National Natural Science Founda-tion of China (Grant No. 60577018 and No. 10674075.)
文摘A novel method of correlation function for analyzing cross-sensitivity between strain and temperature is reported for the first time in this paper. Using the new method,the correlative characteristics between strain and temperature of fiber Bragg grating sensors are studied both theoretically and experimentally The experimental results accord with the theoretical calculations.
基金This work is finically supported by the Project of National Science Foundation of China （NSFC） （Grant No. 50830203, 60908020）, Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, and Program for New Century Excellent Talents in University （NCET- 10-0664）.
文摘The combination of fiber optics with nano-structure technologies and sensitive thin films offers great potential for the realization of novel sensor concepts. Miniatured optical fiber sensors with thin films as sensitive elements could open new fields for optical fiber sensor applications. Thin films work as sensitive elements and transducer to get response and feedback from environments, in which optical fibers are employed to work as signal carrier. This article presents some research work conducted at the National Engineering Laboratory for Optical Fiber Sensing Technologies in recent years. Concrete examples are： Pd/WO3 co-sputtered coating as sensing material for optical hydrogen sensors shows robust mechanical stability and meanwhile good sensing performance; TbDyFe magnetostrictive coating directly deposited on fiber Bragg grating （FBG） demonstrates its possibility of miniature optical magnetic field/current sensors, and 40-pm shift of the FBG wavelength happens at a magnetic field order of 50 mT.
文摘In this paper, the most recent progress as well as challenges of distributed optical fiber sensing （DOFS） in industrial applications is discussed. Compared to the vast market of sensors used to measure strain or temperature, the success of distributed optical fiber sensing （DOFS） at the industrial level is very limited, at best. One of the reasons for this lack of the wider acceptance is the mismatch between the commercially available systems and actual industrial requirements, especially for the spatial resolution and precision. These requirements are organized and clarified in the paper. It also describes the hybrid Brillouin-Rayleigh system, which exhibits capabilities surpassing those of strain gauges. The principles of the system are illustrated considering the fiber calibration methodology. Formulas required for determining strain, temperature, and hydro-pressure are derived and discussed. Finally, the examples of applications are presented.
文摘The key factor of the sensitivity in the FBG-based pH sensor is analyzed in detail. A multi-thin-layer structure of the gel coated cover was proposed and implemented with a special process. The sensors with the coated thickness of 420 ~m, 500 ~m, and 580 ~m were built up, respectively. The corresponding spectral shifts of 0.08nm, 0.13nm, and 0.22nm were detected when the pH sensors were soaked in the pH value of 3-9. Meanwhile, the sensor with the gel layer thickness of 580 ~tm was measured in the optimum measurement time period with the pH value changing from 3-12, in which the detected sensitivity of 52pm/pH was achieved in the pH range of 6-12.
文摘This article describes in detail a technique for model!ng cavity optomechanical field sensors. A magnetic or electric field induces a spatially varying stress across the sensor, which then induces a force on mechanical eigenmodes of the system. The force on each oscillator can then be determined from an overlap integral between magnetostrictive stress and the corresponding eigenmode, with the optomechanical coupling strength determining the ultimate resolution with which this force can be detected. Furthermore, an optomechanical magnetic field sensor is compared to other magnetic field sensors in terms of sensitivity and potential for miniaturization. It is shown that an optomechanical sensor can potentially outperform state-of-the-art magnetometers of similar size, in particular other sensors based on a magnetostrictive mechanism.
基金supported by the National Natural Science Foundation of China(Nos.60837002and61177069)the Ph.D.Programs Foundation of Ministry of Education of China(No.20090009110003)the Fundamental Research Funds for the Central Universities(No.2011YJS214)
文摘A fiber Bragg grating strain sensor,whose reflection bandwidth is insensitive to temperature,is presented.The cross-sec-tional area is designed to change linearly.Under axial stress,there is a linear relationship between stress and average strain.Experimental results show that when temperature increases,reflection center wavelength shifts to longer wavelength,and there is a good linear relationship between center wavelength and temperature.When stress increases,reflection center wavelength shifts to longer wavelength,and reflection bandwidth increases.There are good linear relationships between reflection center wavelength and stress as well as reflection bandwidth and stress.
基金supported by the National Natural Science Foundation of China(Nos.6120506861475133 and 61575170)+4 种基金the College Youth Talent Project of Hebei Province(No.BJ2014057)the Hebei Provincial Natural Science Foundation(No.F2015203270)the Hebei Provincial Science and Technology Program(Nos.15273304D and 14273301D)the"XinRuiGongCheng"Talent Projectthe Excellent Youth Funds for School of Information Science and Engineering in Yanshan University(No.2014201)
文摘In this paper, a novel liquid refractive index （R/） sensor based on fused tapered photonic crystal fiber （PCF） is proposed. It is fabricated by fusing and tapering a section of PCF which is spliced with two single-mode fibers （SMFs）. Due to the fused biconical taper method, the sensor becomes longer and thinner, to make the change of the outside RI has more direct effects on the internal optical field of the PCF, which finally enhances the sensitivity of this sensor. Experimental results show that the transmission spectra of the sensor are red-shifted obviously with the increase of RI. The longer the tapered region of the sensor, the higher the sensitivity is. This sensor has the advantages of simple structure, easy fabri- cation, high performance and so on, so it has potential applications in RI measurement.
基金the Ministry of Education, Singapore (R-143-000-607-112)the National Research Foundation, Prime Minister’s Office, Singapore under its Competitive Research Program (NRF-CRP10-2012-04)Medium Sized Centre Programme
文摘A highly sensitive and selective two-photon sensing scheme for detection of cartap was developed by using Au@Ag bimetallic core-shell nanoparticles.Cartap was found to induce the aggregation of Au@Ag nanoparticles and up to 700-fold enhancement in two-photon photoluminescence.Huge enhancement in two-photon photoluminescence allows achieving a detection limit of as low as 0.0062 mg/kg,which is better than the conventional colorimetric methods.This two-photon sensing scheme has a broad dynamic range and displays excellent selectivity in detection of cartap against over other ten kinds of commonly used insecticides.
文摘An index guiding photonic crystal fiber used in gas sensing applications is presented. The dependency of the confinement loss and relative sensitivity on the fiber parameters and wavelength is numerically investigated by using the full-vectorial finite element method （FEM）. The simulations showed that the gas sensing sensitivity increased with an increase in the core diameter and a decrease in the distance between centers of two adjacent holes. Increasing the hole size of two outer cladding rings, this structure simultaneously showed up to 10% improved sensitivity, and the confinement loss reached 6x 10-4 times less than that of the prior sensor at the wavelength of 1.5 μm. This proved the ability of this fiber used in gas and chemicals sensing applications.
