“…Figure 10 shows the relationship curve between the wavelength shift and the temperature change of the air-medium FBG sensor, and the curve between the wavelength shift and grease-medium FBG sensor. Equations (14) and (15) are calibration curves of the the air-medium and grease-medium FBG sensor obtained by least square fitting, λ a = 0.0186 × 10 −3 T + 1538.548 (14) λ g = 0.01031 × 10 −3 T + 1544.603.…”
Section: Experiments Of Fbg Temperature Sensitivitymentioning
confidence: 99%
“…The Bragg wavelength depends both on physical characteristics (the effective refractive index of the reverse coupling mode, ) of the fiber and the geometrical characteristics (period of the grating, ) of the grating [ 13 , 14 ], the relation between these elements satisfies the light equation …”
A double-thimble-type fiber Bragg grating (FBG) temperature sensor that isolates the stress strain is developed, and the three materials of air, grease, and copper thimble are employed for encapsulating. To investigate the effect of different encapsulation materials on the time constant of the sensors under dynamic conditions, the transient heat conduction mathematical model is built according to the lumped heat capacity (LHC) system and thermal equilibrium theory, and the time constant is solved by an analytical solution. Then, a proportional three-dimensional sensor simulation model is established and the transient heat transfer process is numerically solved by the finite element analysis method. To verify the models, an experimental system is established to test the response speed of the three-type sensor and the experimental data are compared with the analytical and numerical solution results. The results show that the dynamic response performance depends on the encapsulation material parameters; the response speed is faster than recovery speed; and the response speed of the air packaging sensor is more than 20% faster than that of the grease packaging sensor, and more than 30% faster than that of the copper packaging sensor. The smaller the heat storage capacity and the larger the heat transfer coefficient, the faster the sensor’s response speed.
“…Figure 10 shows the relationship curve between the wavelength shift and the temperature change of the air-medium FBG sensor, and the curve between the wavelength shift and grease-medium FBG sensor. Equations (14) and (15) are calibration curves of the the air-medium and grease-medium FBG sensor obtained by least square fitting, λ a = 0.0186 × 10 −3 T + 1538.548 (14) λ g = 0.01031 × 10 −3 T + 1544.603.…”
Section: Experiments Of Fbg Temperature Sensitivitymentioning
confidence: 99%
“…The Bragg wavelength depends both on physical characteristics (the effective refractive index of the reverse coupling mode, ) of the fiber and the geometrical characteristics (period of the grating, ) of the grating [ 13 , 14 ], the relation between these elements satisfies the light equation …”
A double-thimble-type fiber Bragg grating (FBG) temperature sensor that isolates the stress strain is developed, and the three materials of air, grease, and copper thimble are employed for encapsulating. To investigate the effect of different encapsulation materials on the time constant of the sensors under dynamic conditions, the transient heat conduction mathematical model is built according to the lumped heat capacity (LHC) system and thermal equilibrium theory, and the time constant is solved by an analytical solution. Then, a proportional three-dimensional sensor simulation model is established and the transient heat transfer process is numerically solved by the finite element analysis method. To verify the models, an experimental system is established to test the response speed of the three-type sensor and the experimental data are compared with the analytical and numerical solution results. The results show that the dynamic response performance depends on the encapsulation material parameters; the response speed is faster than recovery speed; and the response speed of the air packaging sensor is more than 20% faster than that of the grease packaging sensor, and more than 30% faster than that of the copper packaging sensor. The smaller the heat storage capacity and the larger the heat transfer coefficient, the faster the sensor’s response speed.
“…Fiber optics sensors have been widely used to measure various physical parameters, such as temperature [ 1 ], strain [ 2 ], refractive index [ 3 ], etc., due to their advantages of anti-electromagnetic interference, high resolution, lightweight, and compact size [ 3 , 4 , 5 ]. In recent years, various configurations have been proposed for simultaneous measurement of temperature and strain, including various Mach–Zehnder interferometers (MZIs) [ 6 , 7 , 8 ] and Fabry–Pérot interferometers (FPIs) [ 9 , 10 , 11 ], fiber Bragg gratings (FBGs) [ 12 ], and long-period fiber gratings (LPFGs) [ 13 ]. Among them, MZI- or FPI-based devices are usually realized by splicing different special fibers [ 14 , 15 ], micro-cavity [ 7 ] fabricated by lasers, and fiber tapers [ 16 , 17 ], which have shown outstanding advantages of higher wavelength sensitivity, simple fabrication, and rich structures.…”
A hybrid sensing configuration for simultaneous measurement of strain and temperature based on fiber Bragg grating (FBG) written in an offset multimode fiber (MMF) interferometer using femtosecond laser pulse is proposed and demonstrated. A Mach–Zehnder interferometer is formed by splicing a section of MMF between two single-mode fibers (SMFs) and a high interference fringe of up to 15 dB is achieved. The sensing experimental results show a strain sensitivity of −1.17 pm/με and 0.6498 pm/με for the dip of MZI and Bragg peak, while a temperature sensitivity of 42.84 pm/°C and 19.96 pm/°C is measured. Furthermore, the matrix analysis has found that the strain and temperature resolution of the sensor are as high as ±12.36 με and ±0.35 °C, respectively. In addition, the sensor has merits of simple fabrication, good spectral quality, and high resolution, which shows attractive potential applications in dual-parameter sensing.
“…Fiber Bragg grating (FBG) temperature sensor has been widely used, but its sensitivity is low, usually at the level of pm. [11,12] Although the temperature sensitivity of long period fiber grating (LPFG) temperature sensor [13][14][15] has been improved, it has the problem of cross sensitivity because that it is sensitive to multiple parameters.…”
In order to control the working wavelength range of the fiber surface plasmon resonance (SPR) temperature sensor and realize the wavelength division multiplexing type multi-channel fiber SPR temperature sensor, by comprehensively investigating the influence of liquids with different thermal-optical coefficients and solid packaging materials on the performance of fiber SPR temperature sensor, a dual-channel fiber SPR temperature sensor based on liquid-solid cascade encapsulation was designed and fabricated. The liquid temperature sensing stage encapsulated in capillary worked in 616.03 nm-639.05 nm band, the solid sensing stage coated with pouring sealant worked in 719.37 nm-825.27 nm band, and the two stages were cascaded to form a fiber dual-channel temperature sensor. The testing results indicated that when the temperature range was 35 • C-95 • C, the sensitivity of two-stage temperature detection was −0.384 nm/ • C and −1.765 nm/ • C respectively. The proposed fiber sensor has simple fabrication and excellent performance which can be widely used in various fields of dual-channel temperature measurement and temperature compensation.
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