Sensitivity Of Fiber Bragg Grating Research Articles

A Multiplexing Optical Temperature Sensing System for Induction Motors Using Few-Mode Fiber Spatial Mode Diversity

Induction motors are widely applied in motor drive systems. Effective temperature monitoring is one of the keys to ensuring the reliability and optimal performance of the motors. Therefore, this paper introduces a multiplexed optical temperature sensing system for induction motors based on few-mode fiber (FMF) spatial mode diversity. By using the spatial mode dimension of FMF, fiber Bragg grating (FBG) carried by different spatial modes of optical paths is embedded in different positions of the motor to realize multipoint synchronous multiplexing temperature monitoring. The paper establishes and demonstrates a photonic lantern-based mode division sensing system for motor temperature monitoring. As a proof of concept, the system demonstrates experiments in multiplexed temperature sensing for motor stators using the fundamental mode LP01 and high-order spatial modes LP11, LP21, and LP02. The FBG sensitivity carried by the above mode is 0.0107 nm/°C, 0.0106 nm/°C, 0.0097 nm/°C, and 0.0116 nm/°C, respectively. The dynamic temperature changes in the stator at different positions of the motor under speeds of 1k rpm, 1.5k rpm, 2k rpm with no load, 3 kg load, and 5 kg load, as well as at three specific speed–load combinations of 1.5k rpm_3 kg, 1k rpm_0kg, 2k rpm_5 kg and so on are measured, and the measured results of different spatial modes are compared and analyzed. The findings indicate that different spatial modes can accurately reflect temperature variations at various positions in motor stator winding.

Fiber Bragg gratings fabricated in fibers with different geometries by femtosecond laser written through the coating and their applications in strain sensing and fiber laser

Applications of the type-I fiber Bragg gratings (FBGs) written through the coating (TTC) in strain sensing and tunable distributed Bragg reflector (DBR) fiber lasers were demonstrated. We reported the principle of selecting the distance between the fiber and the phase mask when writing type-I TTC FBGs. Type-I TTC FBGs written in commercially available acrylate-coated fibers with various geometries and their strain responses were demonstrated. Results showed that the strain sensitivity of FBGs increases as the core-diameter decreases, probably due to the waveguide effect. In addition, a continuously tunable DBR fiber laser based on TTC FBGs was achieved with a wavelength tuning range of 19.934 nm around 1080 nm, by applying a strain of 0-21265.8 µɛ to the laser resonant cavity. The wavelength tuning range was limited by the splice point between the gain fiber and the passive fiber for transmitting pump and signal lasers. When the pump power was 100 mW, the relative intensity noises were −97.334 dB/Hz at the relaxation oscillation peak of 880 kHz and −128 dB/Hz at frequencies greater than 3 MHz. The results open a potential scheme to design and implement continuously tunable fiber lasers and fiber laser sensors for strain sensing with a higher resolution.

Immune to temperature interference sensor of carbon dioxide gas concentration based on a single modified fiber Bragg grating.

In this study, a novel method that can detect carbon dioxide (CO2) concentration and realize temperature immunity based on only one fiber Bragg grating (FBG) is proposed. The outstanding contribution lies in solving the temperature crosstalk issue of FBG and ensuring the accuracy of detection results under the condition of anti-temperature interference. To achieve immunity to temperature interference without changing the initial structure of FBG, the optical fiber cladding of FBG and adjacent optical fiber cladding at both ends of FBG are modified by a polymer coating. Moreover, a universal immune temperature demodulation algorithm is derived. The experimental results demonstrate that the temperature response sensitivity of the improved FBG is controlled within the range of 0.00407 nm/°C. Compared with the initial FBG (the temperature sensitivity of the initial FBG is 0.04 nm/°C), it decreases by nearly 10 times. Besides, the gas response sensitivity of FBG reaches 1.6 pm/ppm and has overwhelmingly ideal linearity. The detection error results manifest that the gas concentration error in 20 groups of data does not exceed 3.16 ppm. The final reproducibility research shows that the difference in detection sensitivity between the two sensors is 0.08 pm/ppm, and the relative error of linearity is 1.07%. In a word, the proposed method can accurately detect the concentration of CO2 gas and is efficiently immune to temperature interference. The sensor we proposed has the advantages of a simple production process, low cost, and satisfactory reproducibility. It also has the prospect of mass production.

Highly sensitive optical fibre Bragg grating contact pressure sensor embedded in a polymer layer: Modelling and experimental validation

This paper discusses mathematical modelling and experimental validation of a highly sensitive optical fibre Bragg grating (FBG) contact pressure sensor developed for healthcare applications. Bare FBGs are not very sensitive to pressure (∼3 × 10−3 nm/MPa) but this can be increased by embedding the FBG in a polymer layer which acts as transducer to convert transverse load (pressure) applied to an axial strain, measured by the FBG sensor. The pressure sensitivity of the FBG sensor depends on the mechanical and physical properties such as Young’s modulus, shape and size of the polymer. A finite element analysis (FEA) model is developed to optimise the design parameters of the FBG sensor in order to achieve a high sensitivity. A transfer matrix mathematical formulism is then used to relate the reflection spectrum of the FBG to the strain experienced. Three different shapes, three different sizes and three different polymer materials with different Young’s moduli have been simulated and their wavelength sensitivities related to the transverse pressure. According to the simulation results, the pressure sensitivity of a bare FBG can be increased ∼ 270 times (0.8179 nm/MPa) by selecting an FBG of 3 mm length, embedding it at the horizontal centre of a polymer layer of Young’s modulus of 20 MPa, in the shape of a circular disc with a diameter 5.5 mm and thickness of 1 mm.

Design and realization of a femtosecond-laser-inscribed fiber Bragg grating for accurate measurement of liquid level and liquid density

An exceptionally sensitive liquid level and density sensor system using Femtosecond-Laser-Inscribed Fiber Bragg Gratings is designed and demonstrated utilizing the basic Archimedes’ Law of Buoyancy. The sensor works based on principles of Archimedes’ law of buoyancy and basic strain sensitivity of Fiber Bragg Grating (FBG). A cylindrical mass of 22.5 cm long is suspended from one end of the FBG and whereas the other end of the fiber is fixed. The mass is partially immersed into the liquid under consideration to measure the liquid level as well as liquid density. Following Archimedes’ law of buoyancy, the relative weight of the suspended mass gets reduced and the corresponding shift in Bragg wavelength is measured using an interrogator connected at the fixed end of the sensor lead fiber. The relative weight of the immersed mass also depends on the liquid density. Therefore, a change in liquid density also is reflected by the shift in Bragg wavelength. The system can be calibrated to measure the accurate liquid level and liquid density. A liquid (water) level measurement sensitivity of 5.47 to 5.60 pm/mm is achieved using the system under three times of consecutive experiments which is very close to the simulated value (5.9 pm/mm). A density measurement sensitivity of ∼ 0.71 nm/(gm/cm3) is calculated in this system and experimentally achieved sensitivity is ∼ 0.7 nm/(gm/cm3). The LOD (limit of detection) was also found to be 1.008 gm/cc for the density measurement and the average error during the measurement was 0.0021 nm/(gm/cm3).It is also shown that the density measurement sensitivity is highly dependent on the amount of immersed portion of the suspended mass and more amount of immersed mass is desirable for better sensitivity.

Study of temperature sensing performance of bimetallic layer MFBG

To improve the strength and performance of FBG (fiber Bragg grating), they are often encapsulated and protected or surface metallized. In this paper, based on the thermoelastic theory of J.M.C. Duhamel and F.E. Neumann, a thermal sensitivity model for bimetallic layer MFBG (metalized FBG) is established, and the thermal sensitivity performance parameters are analyzed for MFBG with single metal layers and those with Ni and Ti bimetallic layers deposited on the surface. The thermal sensitivity coefficient of the MFBG gradually stabilizes as the thickness of the metal coating increases. To verify the rationality of the theoretical model, Ni-Ti MFBG (double-layer MFBG with Ni as the outer metal and Ti as the inner metal) were prepared by magnetron sputtering with electroplating for thickening, and the plating process and formulation were optimized. The thermal sensing performance experiments of Ni-Ti MFBG and ordinary bare FBG were conducted together. The metallization of FBG can improve the temperature sensitivity of FBG, and the relative error between the experimental data and the theoretical value is less than 5 %. When h1 (the thickness of the inner metal layer) = 1 µm, h2 (the thickness of the outer metal layer) keeps increasing, the change trend of the temperature sensitivity of Ni-Ti-MFBG is consistent with the conclusion reached in the theory, which strongly proves the validity and reasonableness of the established bimetallic layer MFBG thermal sensing model, and the results of this paper have good theoretical guidance significance for the research on the connection between FBG and electromechanical components.

Design and optimization of medium-high frequency FBG acceleration sensor based on symmetry flexible hinge structure

A flexible hinge fiber Bragg grating (FBG) acceleration sensor based on the symmetry mass block is proposed to address poor transverse performance and lower sensitivity in medium- and high-frequency. The dual mass block design causes the FBG fiber to vibrate while simultaneously being stretched or compressed in the reverse direction. Thus, the FBG's sensitivity is greatly improved, and its deformation is double that of the single hinge construction. MATLAB software theoretically investigates and optimizes the sensor's natural frequency and sensitivity. In contrast, ANSYS analyzes static structural stress and simulation. The implementation of the sensors is assessed through an experimental test. The accelerometer's natural frequency is 1550 Hz, and its working stability frequency range is flat at 400–1000 Hz. The amplitude anti-interference of the sensor is approximately 3.27%, and the average sensitivity's linearity is roughly 66 pm/g. Developing medium and high-frequency vibration data is essential for the health monitoring and evaluation of constructions such as bridges, railroads, and tunnels.

Research on a bimetallic-sensitized FBG temperature sensor.

Temperature measurement is of great significance for research in the health monitoring of large structures and earthquake precursors. Against the frequently reported low sensitivity of fiber Bragg grating (FBG) temperature sensors, a bimetallic-sensitized FBG temperature sensor was proposed. The sensitization structure of the FBG temperature sensor was designed, and the sensor sensitivity was analyzed; the lengths and materials of the substrate and strain transfer beam were analyzed theoretically; 7075 aluminum and 4J36 invar were chosen as bimetallic materials, and the ratio of the substrate length to the sensing fiber length was determined. The structural parameters were optimized; the real sensor was developed, and its performance was tested. The results suggested that the sensitivity of the FBG temperature sensor was 50.2 pm/°C, about five times than that of a bare FBG sensor, and its linearity was more than 0.99. The findings offer a reference for developing sensors of the same type and further improving the sensitivity of the FBG temperature sensors.

Validation of Packaged Clad-Etched Fiber Bragg Grating as Underwater Acoustic Sensor

The low intrinsic pressure sensitivity of fiber Bragg grating (FBG) sensors impede their potential applications in the field of hydro-acoustics. This article demonstrates a simple, yet effective way of improving the aggregate hydro-acoustic sensitivity of a bare FBG sensor through clad-etching of the fiber sensor followed by a side-hole polymer packaging. The proposed underwater acoustic sensor system is characterized and validated with a standard lead zirconate titanate (PZT)-based hydrophone under various experimental conditions. This is the first time, to the best of our knowledge, such a high acoustic pressure sensitivity enhancement of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 50$ </tex-math></inline-formula> dB, in comparison with a bare FBG sensor, is reported using a conventional and highly operationally stable wavelength interrogation technique. The minimum detectable acoustic pressure is calculated to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 1$ </tex-math></inline-formula> Pa/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(\text {Hz})^{1/2}$ </tex-math></inline-formula> with a maximum responsivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 100$ </tex-math></inline-formula> nm/MPa in the investigated frequency range, with excellent performances in terms of linear response and repeatability. The dynamic range, in the present scenario, is only limited by the range of the interrogation system. The proposed underwater acoustic sensor along with the interrogation technique is a highly compact and cost-effective method for underwater acoustic sensing. Thus, the obtained results can be used for developing and producing long, narrow hydro-acoustic quasi-distributed sensor arrays for marine explorations and other applications.

Cantilever vibration sensor based on Fiber Bragg Grating temperature compensation

To improve the sensitivity of fiber Bragg grating (FBG) vibration sensor and reduce the influence of temperature on vibration detection, an FBG vibration sensor with equal strength beam as elastic structure and temperature self-compensated is proposed. The working principle of the sensor is analyzed, the resonant frequency and the sensitivity are derived through the formula, the structural parameters are optimized, and its good response characteristics are proved by experiments. The theory of the proposed sensor is verified by experiments, and the experimental results show that the temperature impact on the sensor structure is reduced to 0.17 pm/°C in the range of 30–75°C. The sensor has a good response flat region at 20–220 Hz, the sensitivity is 149.8 pm/g. and the transverse sensitivity is only 3.95 % of the sensitivity in the working direction. Experiments show that the sensor has good comprehensive characteristics. Therefore, the sensor has great application prospect in vibration signal detection in the environment with obvious temperature changes, such as oil exploration, aerospace and so on.

Measurement of Cable Force through a Fiber Bragg Grating-Type Thin Rod Vibration Sensor and Its Application.

The key to evaluating the health status of cable-stayed bridges lies in the accuracy of cable force measurement. When measuring the cable force using the conventional frequency method, the clearance between the bracing cable and the protective tube is typically disregarded. Moreover, due to their large size, existing vibration sensors are difficult to install into protective tubes for steel strand-type bracing cables to measure the cable force. To address the above difficulties, a type of thin rod vibration sensor only 5 mm in diameter was designed based on the high sensitivity of Fiber Bragg grating (FBG), and high-throughput data processing software for engineering calculation (EC) was self-developed. Then, the recognition principle of the thin rod vibration sensor was theoretically analyzed and a step-by-step tension test was carried out. The results demonstrated that the relative error of the cable force measured by the thin rod vibration sensor within 12.865 Hz was less than 5% and the sensitivity reached 28.7 pm/Hz, indicating its high measurement precision. Upon subsequent application of the thin rod vibration sensor to a monitoring test in the field, the relative error of the fundamental frequency between artificial and natural excitations was less than 4%. In addition, the error relative to both the theoretical frequency and the third-party sampling frequency was less than 5%, further verifying the accuracy and applicability for monitoring the cable force of bridges under natural excitation. Compared with the traditional cantilever FBG sensor, the improved sensor with supporting data processing software has the advantages of small cross-section, high reliability, and good sensitivity. The research results can provide a reference for the subsequent accurate measurement of cable force and the development of a supporting sensor data processing system.

Temperature and strain sensitivities of a groove bonded fiber Bragg grating at room and cryogenic temperatures

Optical fiber Bragg gratings (FBGs) are well suited for applications as temperature or/and strain sensors in harsh environments, e.g., detecting thermal hot spots in high-temperature superconductor (HTS) fusion energy magnets at cryogenic temperatures and high radiation environments. To maximize the signal-to-noise ratio (SNR) of the FBGs to a hot spot, we propose to have them mounted in V-shaped grooves of HTS' copper former. To investigate the differences between different adhesives on transferring strain and heat in this configuration, five arrays of FBGs are mounted in the V-shaped grooves of a copper dog-bone using Scotch-Weld epoxy, Stycast 2850 FT, Apiezon N, and Loctite 5145 silicone. The copper is cycled through tensile forces in a modified universal tensile tester, subjected to a thermal cycle between 293 K and 77 K, and exposed to heat pulse propagations at 293 K and 80 K. The FBGs that are bonded using Stycast show the highest temperature and strain sensitivities at room and cryogenic temperatures. No major differences in the temperature and strain sensitivities have been found between Ormocer and polyimide coated FBGs. Apiezon N is found to transfer strain consistently well below 245 K, which is comparable with other bonding materials in the temperature range between 77 K and 110 K. The FBGs bonded with the four adhesives in the V-groove configurations are shown to have comparable SNRs to a temperature rise of 20 K at 80 K. This paper emphasizes the importance of maximizing the thermal strain transferred from the host material through the bonding agents to achieve high temperature sensitivity of FBGs.

Cross spring leaf-based high-sensitivity low-frequency dual-FBG acceleration sensor.

The measurement of low-frequency vibration signals is of great significance in seismic monitoring, health monitoring of large and medium-sized engineering structures, and resource exploration. In view of the low sensitivity of fiber Bragg grating (FBG) acceleration sensors in measuring low-frequency vibration signals, a high-sensitivity, low-frequency dual-FBG acceleration sensor is proposed. Theoretical formula derivation and ANSYS software were used to optimize the design and simulation analysis of the structural parameters of the sensor. The real sensor was made based on the simulation results, and a test system was established to test its performance. According to the findings, the natural frequency of the acceleration sensor is 65 Hz. It gives a flat sensitivity response in the low frequency band of 3-45 Hz. The dynamic range is 92.63 dB at 10 Hz, the acceleration sensitivity is 1498.29 pm/g, and the linearity R2 is 0.9998. The relative standard deviation of the sensor repeatability is 1.75%, and the transverse crosstalk in the working frequency band is -33.99dB. Designed with a high sensitivity and excellent temperature compensation capacity in the low-frequency band, the designed sensor is suitable for low- and medium-frequency vibration detection in engineering.

Study on strain sensing property of fiber Bragg grating based on surface strain measurement of mechanical structure.

Strain monitoring is of great significance to identify the failure of key mechanical components and ensure the good operation of mechanical equipment. In terms of the common issue of the low sensitivity of fiber Bragg grating (FBG) strain sensor in strain measurement on the mechanical structure surface, this paper describes a flexible hinge strain sensor with the FBG as the sensitive element. A theoretical analysis of the sensitivity of the sensor is performed, a copper alloy material with a large elastic modulus is selected, the simulation analysis and optimization design for the structural parameters of the sensor are carried out by using ANSYS and Solidworks software, then the object of the sensor is developed according to the simulation results, and finally, the performance of the sensor is tested. The results show that the maximum deformation the sensor can measure is 0.5299 µε, the sensitivity of the sensor is ∼1.8870 pm/µε, which is approximately twice that of the bare FBG sensor, the linearity is greater than 99%, and the relative standard deviation of the repeatability is 0.9%. The results of the study provide a reference for developing the optical fiber strain sensor and further improving its sensitivity.

Fiber bragg grating sensors to monitor strain response of epoxy resin during curing and cryogenic temperature

The epoxy resin is one of the critical components of large-scale superconducting magnets which find wide applications in magnetic confinement fusion, high energy accelerator and magnetic resonance imaging. In general, magnetic confinement fusion, high energy accelerator and magnetic resonance will be used at cryogenic temperatures. An approach with respect to real-time monitor of epoxy curing and cryogenic process is practically significant for magnetic reliability, maintainability as well as future mass production. Fiber Bragg Grating (FBG) sensors are excellent candidates of this measurement for their anti-electromagnetic interference characteristics and high sensitivity. The aim of this work is to use the embedded Fiber Bragg Gratings (FBG) to obtain real-time strain response of curing epoxy, and the strain change of the epoxy at cryogenic temperature from 4.2K to 300K. An FBG pre-tensioning device was designed to keep the FBG embedded in the epoxy in a stretched state during the epoxy curing process. Moreover, strain gauge sensors were also embedded to monitor the curing process at the same time. There are subtle differences in strain values obtained by the two sensors, which illustrate higher sensitivity of FBGs. This work verifies the reliability of FBG monitoring the strain response of epoxy during curing process as well as the cryogenic service.

An Omni-Azimuth Angle Sensor for Tilt Measuring Based on FBG Array

An omni-azimuth angle sensor for tilt measuring based on fiber Bragg grating (FBG) array is proposed. It is designed based on the sensitivity of FBG to axial traction. The sensor consists of a mass block and a cube frame connected by an FBG array. The FBG array consists of four FBGs. When the sensor is tilted at different angles, the axial traction of each FBG will change due to the pull of the mass block. The tilt angle of the sensing unit can be obtained by calculating the magnitude and direction of the resultant traction of the four FBGs. The array design and measurement theory of the sensor are introduced, and the sensitivity of the sensor is discussed. Experimental results show that the FBG array can be used to measure the omni-azimuth angle. The angle sensitivity varies unevenly with the tilt angle and the range of variation is 0.08 nm/° to 0.4593 nm/°. Using the spectrometer with an accuracy of 0.01 nm, the angle resolution ranges from 0.125° to 0.0218°. The array effectively extends the measurement range of the tilt sensor, and reduces the number of FBGs as much as possible on the basis of achieving omni-azimuth angle measurement.

Ultrasonic frequency response of fiber Bragg grating under direct and remote adhesive bonding configurations

Ultrasonic inspection based structural health monitoring is a powerful technique for damage detection in a structure. Ultrasonic waves are often excited at different frequencies to detect damages of different sizes, therefore understanding the frequency response of the sensor can be used to optimize the sensor performance. Fiber Bragg gratings (FBGs) are widely used for this ultrasound collection. The sensitivity of FBGs to a particular ultrasonic frequency is a function of the FBG length and the ultrasonic wavelength. Recently the authors demonstrated that its ultrasound sensitivity is improved for some conditions when the FBG is bonded at a distance away from the adhesive bond, referred to as remote bonding. However, the frequency response of this configuration has not been studied. Therefore, in this paper we measure and compare the ultrasonic frequency responses between a conventional directly bonded FBG and remotely bonded FBG. In theory, the FBG sensitivity varies as a function of ultrasound wavelength-to-grating length (λ/L) ratio. Therefore, for this experimental study, we maintain L constant and vary λ by changing the frequency of the input ultrasonic waves. We demonstrate that there is a region, below a cut-off values of λ/L, for which the remotely bonded FBG output has a higher sensitivity to the Lamb wave amplitude than the directly bonded FBG. The exact value of this λ/L cut-off depends on the mechanical properties of the structure, the windowing of the input Lamb wave, and the FBG properties. We also demonstrate that windowing the Lamb wave excitation signal has a similar affect to apodizing the FBG sensor in modifying the sensitivity response curve.

Sensitivity Enhancement of Fiber-Optic Accelerometers Using Thin-Cladding Fiber Bragg Gratings

We propose and demonstrate a method for improving the sensitivity of fiber Bragg grating (FBG) based accelerometers. The method employs a short FBG inscribed in single mode fiber (SMF) with cladding substantially thinner than 125 μm. The resultant stress concentration at the FBG significantly improved the axial strain response compared with 125-μm-diameter fiber. A 50-μm-diameter FBG fixed on a cantilever beam was used to experimentally demonstrate this sensitivity enhancement. The accelerometer has a working frequency bandwidth from 0.5 Hz to 30 Hz with a sensitivity of 2150±30 pm/g, amounting to 5-fold sensitivity enhancement compared to 125-μm-diameter fiber.

Simultaneous AC and DC measurement based on an FBG-magnetostrictive fiber sensor.

Simultaneous alternating current (AC) and direct current (DC) measurement is demonstrated with a new fiber sensor that combines fiber Bragg gratings (FBGs) with giant magnetostrictive materials (GMMs). Deformation of GMMs, proportional to the central wavelength shift of FBGs, is different when applying DC and AC to a solenoid where the whole sensing structure is located. DC introduces a constant deformation while AC causes a periodic variation. Therefore, the central wavelength of FBG has a periodic harmonic variation, which makes it possible to demodulate the values of DC and AC at the same time. In addition, the proposed method has potential significance for reducing temperature cross talk caused by the thermal sensitivity of FBGs. The experimental results show that the sensitivity of the AC current can reach up to 0.090576 nm/A in the range of 0 to 1 A, and in different AC environments, the sensitivity of the DC current can reach up to 0.2378 nm/A.

Pengaruh Sensitivitas Suhu Dengan Metode Couple-Mode Terhadap Fiber Bragg Grating Fiber Optik

The characteristics of Fiber Bragg Grating (FBG) related to change of reflection power and wavelength shift in the fiber optic due to changes in temperature. Furthermore, the refractive index alo affects the sensitivity of FBG. Using the Coupled-mode theory, the derivation of mathematical formula can be found to justify the effect of temperature in FBG. Also, the Coupled-mode theory is integrated numerically by the Transfer Matrix method to achieve the final equation of the effect of temperature in FBG. To obtain optimal results, several different parameter values are given to be analyzed. The results show that the temperatures are affecting the wavelength but have no effect on the peak of reflection power. In addition, by increasing the temperature and value of the refractive index will affect the enhancement of the sensitivity of FBG. These characteristics are a good opportunity to produce filters, sensors, or other applications by utilizing the characteristics of temperature in FBG.