The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Yong Zhao - One of the best experts on this subject based on the ideXlab platform.

  • high Sensitivity refractive index sensor based on splicing points tapered smf pcf smf structure mach zehnder mode interferometer
    Sensors and Actuators B-chemical, 2016
    Co-Authors: Qi Wang, Yong Zhao, Lingxin Kong, Yunli Dang, Yongwei Zhang, Haifeng Hu, Jin Li
    Abstract:

    Abstract The paper proposed and studied a Mach-Zehnder mode interferometric refractive index sensor, which is based on splicing points tapered SMF-PCF-SMF (SMF, single-mode fiber; PCF, photonic crystal fiber) structure. For the reason that the effective refractive index of photonic crystal fiber cladding high-order modes near fiber core are more sensitive to surrounding refractive index changes, the refractive index Measurement Sensitivity of splicing points tapered SMF-PCF-SMF Mach-Zehnder mode interferometer can be enhanced further through tapering the splicing points. Relations between refractive index Measurement Sensitivity and photonic crystal fiber length and taper waist diameter are studied through numerical simulations and experiments. Simulation and experimental results show that Sensitivity will be increased with the increase of photonic crystal fiber length and the decrease of taper waist diameter. In the refractive range of 1.3333–1.3737, splicing points tapered SMF-PCF-SMF Mach-Zehnder mode interferometer with PCF length of 4 cm and taper waist diameter of 60.4 μm has refractive index Measurement Sensitivity of 260.8 nm/RIU, compared with Sensitivity of 224.2 nm/RIU of direct splicing SMF-PCF-SMF Mach-Zehnder mode interferometer with PCF length of 4 cm, the Sensitivity increased by 16.3%. The research shows that the sensing structure is with good linearity and repeatability.

  • optimization of cascaded fiber tapered mach zehnder interferometer and refractive index sensing technology
    Sensors and Actuators B-chemical, 2016
    Co-Authors: Qi Wang, Wenqing Wei, Mengjuan Guo, Yong Zhao
    Abstract:

    Abstract A novel refractive index sensor with high Sensitivity based on Mach–Zehnder interferometer formed by cascaded two single-mode fiber tapers was proposed and experimentally demonstrated. The dip of the measured spectrum signal caused by Mach–Zehnder interference shifted obviously when the surrounding refractive index changed. The approximate linear relationship between surrounding refractive index and spectrum dip wavelength shift was obtained experimentally. The Measurement Sensitivity up to 158.4 nm/RIU was showed with the surrounding RI ranged from 1.33 to 1.3792, which meant the Measurement resolution about 6.3 × 10 −6 could be implemented if wavelength shift Measurement resolution of the optical spectrum analyzer is 1 pm. Meanwhile, its ease of fabrication makes itself a low-cost alternative to existing sensing applications.

  • a novel current sensor based on magnetic fluid and fiber loop cavity ring down technology
    IEEE Sensors Journal, 2015
    Co-Authors: Qi Wang, Ji Xia, Xu Liu, Yong Zhao
    Abstract:

    A novel current sensing system, based on magnetic fluid (MF) film and fiber loop cavity ring-down (CRD) technology, is proposed and demonstrated for the first time. In the sensing system, a MF film whose loss coefficient can be affected by magnetic field is inserted in the ring cavity as the sensitive device. The MF film is made by etching center of two glass slides and sealing MF with a volume concentration of $C=3.6$ % in it. This structure is used as the sensitive device in the ring cavity. In this paper, a fiber loop CRD sensing system has been established for electric current Measurement, and a theoretical model for optimizing coupling ratio of the two couplers in the ring cavity has been presented. The performances of the electric current sensor are evaluated by applying different magnetic fields generated by current to detect decay constants. It can be concluded from the experimental results that a magnetic field Measurement Sensitivity of 0.00033 T/ $\mu \text{s}$ is reached, corresponding to a current Measurement Sensitivity of 3.3 mA/ $\mu \text{s}$ . The current Measurement method based on CRD technology and MF provides a new way for research and applications in the field of modern electrical engineering.

  • magnetic fluid filled optical fiber fabry perot sensor for magnetic field Measurement
    IEEE Photonics Technology Letters, 2014
    Co-Authors: Yong Zhao, Dan Wang, Qi Wang
    Abstract:

    Magnetic fluid is a new type of optical functional material, which has interesting optical characteristics under an external magnetic field. In this letter, the magneto-optical characteristic of the magnetic fluid was adopted to form a novel fiber-optic magnetic field sensor. The sensor probe was composed of an extrinsic fiber Fabry-Perot interferometer and magnetic fluid. The refractive index of the magnetic fluid would be changed with the increase of magnetic field. Preliminary experiment was carried out to verify the feasibility of the sensor. The magnetic field Measurement Sensitivity was 0.0431 nm/Gs in the experiment. The Measurement resolution was better than 0.5 Gs at the Measurement range from 0 to 400 Gs. The sensor has the advantages of simple structure, compact size, and easy fabrication.

  • hollow core photonic crystal fiber fabry perot sensor for magnetic field Measurement based on magnetic fluid
    Optics and Laser Technology, 2012
    Co-Authors: Yong Zhao, Yu Ying, Qi Wang
    Abstract:

    Abstract Based on the characteristic of magnetic-controlling refractive index, the magnetic fluid filled in hollow-core photonic crystal fiber (HC-PCF) can be used as the sensitive medium in the cavity of a fiber Fabry–Perot (F–P) magnetic field sensor. The structure and the sensor principle are introduced. The theoretical simulations of the mode distribution of the HC-PCF filled with the magnetic fluid and the sensor output spectra are discussed in detail. The sensor multiplexing capability is indicated as well. Magnetic field Measurement Sensitivity is about 33 pm/Oe based on the proposed sensor.

Qi Wang - One of the best experts on this subject based on the ideXlab platform.

  • high Sensitivity refractive index sensor based on splicing points tapered smf pcf smf structure mach zehnder mode interferometer
    Sensors and Actuators B-chemical, 2016
    Co-Authors: Qi Wang, Yong Zhao, Lingxin Kong, Yunli Dang, Yongwei Zhang, Haifeng Hu, Jin Li
    Abstract:

    Abstract The paper proposed and studied a Mach-Zehnder mode interferometric refractive index sensor, which is based on splicing points tapered SMF-PCF-SMF (SMF, single-mode fiber; PCF, photonic crystal fiber) structure. For the reason that the effective refractive index of photonic crystal fiber cladding high-order modes near fiber core are more sensitive to surrounding refractive index changes, the refractive index Measurement Sensitivity of splicing points tapered SMF-PCF-SMF Mach-Zehnder mode interferometer can be enhanced further through tapering the splicing points. Relations between refractive index Measurement Sensitivity and photonic crystal fiber length and taper waist diameter are studied through numerical simulations and experiments. Simulation and experimental results show that Sensitivity will be increased with the increase of photonic crystal fiber length and the decrease of taper waist diameter. In the refractive range of 1.3333–1.3737, splicing points tapered SMF-PCF-SMF Mach-Zehnder mode interferometer with PCF length of 4 cm and taper waist diameter of 60.4 μm has refractive index Measurement Sensitivity of 260.8 nm/RIU, compared with Sensitivity of 224.2 nm/RIU of direct splicing SMF-PCF-SMF Mach-Zehnder mode interferometer with PCF length of 4 cm, the Sensitivity increased by 16.3%. The research shows that the sensing structure is with good linearity and repeatability.

  • optimization of cascaded fiber tapered mach zehnder interferometer and refractive index sensing technology
    Sensors and Actuators B-chemical, 2016
    Co-Authors: Qi Wang, Wenqing Wei, Mengjuan Guo, Yong Zhao
    Abstract:

    Abstract A novel refractive index sensor with high Sensitivity based on Mach–Zehnder interferometer formed by cascaded two single-mode fiber tapers was proposed and experimentally demonstrated. The dip of the measured spectrum signal caused by Mach–Zehnder interference shifted obviously when the surrounding refractive index changed. The approximate linear relationship between surrounding refractive index and spectrum dip wavelength shift was obtained experimentally. The Measurement Sensitivity up to 158.4 nm/RIU was showed with the surrounding RI ranged from 1.33 to 1.3792, which meant the Measurement resolution about 6.3 × 10 −6 could be implemented if wavelength shift Measurement resolution of the optical spectrum analyzer is 1 pm. Meanwhile, its ease of fabrication makes itself a low-cost alternative to existing sensing applications.

  • a novel current sensor based on magnetic fluid and fiber loop cavity ring down technology
    IEEE Sensors Journal, 2015
    Co-Authors: Qi Wang, Ji Xia, Xu Liu, Yong Zhao
    Abstract:

    A novel current sensing system, based on magnetic fluid (MF) film and fiber loop cavity ring-down (CRD) technology, is proposed and demonstrated for the first time. In the sensing system, a MF film whose loss coefficient can be affected by magnetic field is inserted in the ring cavity as the sensitive device. The MF film is made by etching center of two glass slides and sealing MF with a volume concentration of $C=3.6$ % in it. This structure is used as the sensitive device in the ring cavity. In this paper, a fiber loop CRD sensing system has been established for electric current Measurement, and a theoretical model for optimizing coupling ratio of the two couplers in the ring cavity has been presented. The performances of the electric current sensor are evaluated by applying different magnetic fields generated by current to detect decay constants. It can be concluded from the experimental results that a magnetic field Measurement Sensitivity of 0.00033 T/ $\mu \text{s}$ is reached, corresponding to a current Measurement Sensitivity of 3.3 mA/ $\mu \text{s}$ . The current Measurement method based on CRD technology and MF provides a new way for research and applications in the field of modern electrical engineering.

  • magnetic fluid filled optical fiber fabry perot sensor for magnetic field Measurement
    IEEE Photonics Technology Letters, 2014
    Co-Authors: Yong Zhao, Dan Wang, Qi Wang
    Abstract:

    Magnetic fluid is a new type of optical functional material, which has interesting optical characteristics under an external magnetic field. In this letter, the magneto-optical characteristic of the magnetic fluid was adopted to form a novel fiber-optic magnetic field sensor. The sensor probe was composed of an extrinsic fiber Fabry-Perot interferometer and magnetic fluid. The refractive index of the magnetic fluid would be changed with the increase of magnetic field. Preliminary experiment was carried out to verify the feasibility of the sensor. The magnetic field Measurement Sensitivity was 0.0431 nm/Gs in the experiment. The Measurement resolution was better than 0.5 Gs at the Measurement range from 0 to 400 Gs. The sensor has the advantages of simple structure, compact size, and easy fabrication.

  • hollow core photonic crystal fiber fabry perot sensor for magnetic field Measurement based on magnetic fluid
    Optics and Laser Technology, 2012
    Co-Authors: Yong Zhao, Yu Ying, Qi Wang
    Abstract:

    Abstract Based on the characteristic of magnetic-controlling refractive index, the magnetic fluid filled in hollow-core photonic crystal fiber (HC-PCF) can be used as the sensitive medium in the cavity of a fiber Fabry–Perot (F–P) magnetic field sensor. The structure and the sensor principle are introduced. The theoretical simulations of the mode distribution of the HC-PCF filled with the magnetic fluid and the sensor output spectra are discussed in detail. The sensor multiplexing capability is indicated as well. Magnetic field Measurement Sensitivity is about 33 pm/Oe based on the proposed sensor.

J H Knight - One of the best experts on this subject based on the ideXlab platform.

  • Sensitivity of time domain reflectometry Measurements to lateral variations in soil water content
    Water Resources Research, 1992
    Co-Authors: J H Knight
    Abstract:

    The spatial responses of two types of time domain reflectometry (TDR) probes used for measuring the water content of soils and other porous materials are examined. We investigate the effect of spatial variation in the water content of the sample on the measured value of the water content for both the coaxial cylinders probe and the two parallel wires probe. The response of the instrument to water content distributions that are perturbed slightly from a uniform distribution is calculated, using the conventional electrostatic treatment of electromagnetic wave propagation in the transverse electro-magnetic (TEM) mode. Under this small perturbation assumption, we show that the spatial weighting function is approximately proportional to the distribution of electromagnetic energy between the electrodes for uniform water content, calculated from a solution of Laplace's equation for each probe type. For coaxial probes, most of the energy (and hence most of the Measurement Sensitivity) is concentrated around the inner cylinder in a “skin effect” if the ratio of the radii of the inner and outer cylinders is too small. For parallel wire probes, most of the Measurement Sensitivity is close to the wires if the wire diameter is too small compared to the spacing between them. This can cause significant errors if there is an air gap close to the wires or soil around the wires has been compacted by the process of inserting them into the soil.

Min Li - One of the best experts on this subject based on the ideXlab platform.

  • design of output feedback controller for stochastic feedforward systems with unknown Measurement Sensitivity
    Isa Transactions, 2020
    Co-Authors: Hanfeng Li, Xianfu Zhang, Min Li
    Abstract:

    Abstract This paper investigates the problem of output feedback control for a class of stochastic feedforward systems with unknown Measurement Sensitivity. Unknown Measurement Sensitivity is only a bounded continuous function and its derivative is not guaranteed. To solve the considered problem, the low-gain linear K-filters are performed without using the information of the output, and a gain design method based on backstepping is proposed to construct an output feedback controller. By the stochastic stability theory, the asymptotically stable in probability of the closed-loop control system is analyzed. A nonlinear liquid level control resonant circuit system with unknown Measurement Sensitivity is given to demonstrate the effectiveness of the proposed control scheme.

Yanbiao Liao - One of the best experts on this subject based on the ideXlab platform.

  • differential fbg sensor for temperature compensated high pressure or displacement Measurement
    Optics and Laser Technology, 2004
    Co-Authors: Yong Zhao, Yanbiao Liao
    Abstract:

    Abstract A differential fiber Bragg grating (FBG) sensor with a free active element bulk-modulus for high-pressure (or displacement) Measurement is presented. Based on the differential Measurement method and an isosceles triangle cantilever structure, problems of cross-Sensitivity and chirped signal in FBG sensor are improved both theoretically and experimentally. Preliminary experiments indicate that temperature-compensated Measurement results agree well with the theoretical analysis. Displacement Measurement Sensitivity is ∼1.75 pm / μm , and the estimated pressure Measurement resolution can reach 0.27 MPa in case the wavelength shift Measurement resolution is 0.01 nm .

  • simultaneous Measurement of down hole high pressure and temperature with a bulk modulus and fbg sensor
    IEEE Photonics Technology Letters, 2002
    Co-Authors: Yong Zhao, Yanbiao Liao
    Abstract:

    A free active element bulk-modulus-based fiber Bragg grating (FBG) sensor for down-hole pressure and temperature Measurement is presented. With a differential Measurement method and an isosceles triangle cantilever structure, problems of cross-Sensitivity and chirped-signal in FBG sensors are solved. Simulation results indicate that the Measurement Sensitivity in measuring pressure and temperature is estimated to be /spl sim/8.5 pm/MPa in a range from standard atmosphere pressure to 100 MPa and /spl sim/27.5 pm//spl deg/C from 20 to 200/spl deg/C, respectively.