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- 摘要
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- 实验方案
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Performance improved tunable millimeter-wave signal generation employing UFBG based AOTF with bit walk-off effect compensation
摘要： A scheme for the generation of mm-wave signals at different frequencies with improved performance is proposed and demonstrated by employing a uniform fiber Bragg grating based acousto-optic tunable filter (UFBG-AOTF). The different frequencies carry different information at a required data rate according to their application. This method reduces the complexity of the system by alleviating the cascaded Mach-Zehnder modulators (MZM) and a good transmission performance can be achieved by the FBG. In the previous system, the distance of transmission is reduced to 15 km due to bit walk-off effect and it also reduces the BER values at larger distances. In the proposed system, the bit walk-off effect is discussed and compensated to increase the transmission distance up to 60 km. The simulation results along with clear eye-diagrams show that the BER values are improved at larger distances than the previous system which proves the performance improvement of the proposed system.
关键词： optical millimeter-wave,radio-over-fiber,bit walk-off effect,acousto-optic tunable filter,uniform fiber Bragg grating
更新于2025-09-19 17:15:36
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Investigation of sensitivity enhancing and temperature compensation for fiber Bragg grating (FBG)-based strain sensor
摘要： This paper developed a novel method and relevant mechanical configurations to enhance strain sensitivity and realize temperature compensation simultaneously for fiber Bragg grating (FBG)-based strain sensor. The theoretical strain amplification model and temperature compensation model of the designed method and the manufactured sensor specimen were derived based on the theory of elastic mechanics and the methodology of matrices. The established theoretical sensing models were validated through finite element method (FEM) and experimental tests. The theoretical, FEM, and experimental results show good consistency. The overall sensitivities of the two FBGs in the developed sensor achieve 7.72 pm/με and ?2.94 pm/με respectively, which are respectively 6.43 and ?2.45 times of the strain sensitivity of a bare fiber Bragg grating strain sensor. The decoupling of strain and temperature was implemented theoretically and verified experimentally. The developed sensor in this paper can be used for long-term small-amplitude micro-strain monitoring in varying temperature environments for vital mechanical equipment.
关键词： Strain,Lever structure,Fiber Bragg grating,Sensitivity enhancement,Temperature compensation
更新于2025-09-19 17:15:36
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Analysis of Residual Stress in Electrical Penetration Assembly Based on a Fiber Bragg Grating Sensor
摘要： An important factor for maintaining hermeticity of a metal-to-glass sealed electrical penetration assembly (EPA) is the residual stress in the sealing glass, which is generated during the EPA sealing process. A novel method to investigate and optimize the sealing process of EPAs, based on a fiber Bragg grating (FBG) sensor, is proposed in this research. An FBG was well bonded with sealing glass to measure the parameters of the glass during the sealing process. The temperature change during the heating process was able to be measured by Bragg wavelength shift. After the sealing glass solidified and dropped to room temperature, the residual stress was determined and the effect of temperature was minimized because the temperature before and after the sealing process was the same as room temperature. The curing temperature of the sealing glass was evaluated to specifically investigate the solidification process of the EPA. This study provides a basis for online stress and temperature monitoring of EPAs under external loads in nuclear power plants.
关键词： electrical penetration assembly,embeddable technology,sealing process analysis,residual stress,fiber Bragg grating
更新于2025-09-19 17:15:36
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Fiberoptic microindentation technique for early osteoarthritis diagnosis: an in vitro study on human cartilage
摘要： In this study, the capability of a fiber optic microindenter sensor to discriminate between healthy and slightly degenerated human articular cartilage samples is demonstrated. The purely optical indenter sensor is characterized by extremely reduced dimensions (0.125 mm in diameter and 27 mm in length) in comparison to existing indenter probes offering advantages for endoscopic deployment. The indenter sensor is intended to assist the surgeon in the identification of damaged articular cartilage. From each of seven specimens of human tibia plateau three samples showing different Outerbridge grading were extracted. On each sample stress-relaxation measurements were performed with eight indentation steps, each step being 40 μm and the relaxation of the material was observed for 240 s after each step. A viscoelastic model was used to fit the relaxation and to extract the characteristic parameters according to the model. A highly significant difference in stiffness (p value <0.01) was observed between the native (grade 0) and early diseased (grade 1) human cartilage samples demonstrating the potential of the fiber optic indenter for the diagnosis of cartilage breakdown.
关键词： Cartilage biomechanics,Indentation,Fiber Bragg grating,Osteoarthritis
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - Structural Shape Estimation by Mode Shapes Using Fiber Bragg Grating Sensors: A Genetic Algorithm Approach
摘要： Structural shape estimation is of great interest in many engineering fields. During operation, however, the monitoring of structural displacements is often difficult. This article discuss structural shape estimation using a minimal number of fiber Bragg grating sensors. A strain to displacement transformation matrix is derived using mode shapes, to estimate the global displacement of a structure from measured discrete strain data. The number of sensors and sensor layout for the shape estimation is optimized using genetic algorithm. Static and dynamic displacement experiments are conducted to verify the algorithm. The results show that the estimated displacements match well with those measured displacements.
关键词： Fiber Bragg Grating,Mode shapes,Genetic Algorithm,Sensor,Shape estimation
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - A Fiber Bragg Grating Strain Sensor-Based Glove to Accurately Measure the Bend Angle of the Finger Flexed at the Proximal Interphalangeal Joints
摘要： Accurate measurement of finger joint angles is very important in the fields such as rehabilitation, bionics, etc. In this paper, we present a fiber Bragg grating (FBG) sensor-based flexure sensing glove to measure the finger joint angles with high accuracy. We evaluate its accuracy and repeatability on four human subjects by measuring their proximal interphalangeal (PIP) joint angles of the index, middle and the ring fingers. Our glove showed excellent agreement (R-Squared: 0.9985) with the inertial measurement unit (IMU) sensor readings. The glove outperforms several existing sensors exhibiting a maximum error (1.42 degrees), mean error (0.45 degrees) and maximum standard deviation (0.56 degrees). In the future, the study will be extended to all the joints.
关键词： rehabilitation,flexure sensor,instrumented glove,fiber Bragg grating
更新于2025-09-19 17:15:36
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Wavelength-switchable erbium-doped fiber laser incorporating fiber Bragg grating array fabricated by infrared femtosecond laser inscription
摘要： Wavelength-switchable fiber laser systems have many potential applications. Herein, the use of an erbium-doped fiber laser based on parallel fiber Bragg gratings (FBGs) (ASE: amplified spontaneous emission; BRM: broadband reflection mirror; CCD: charged-coupled device; EDFL: erbium-doped fiber laser; FBG: fiber Bragg gratings; IR: infrared; MZI: Mach–Zehnder interferometer; OSA: optical spectrum analyzer; OC: output coupler; PC: polarization controller; SNR: signal-to-noise ratios; 3D: three-dimensional; wavelength division multiplexing (WDM)) is proposed to achieve C + L band triple-wavelength-switchable laser output at approximately 1.5 μm. In the proposed system configuration, three parallel FBGs with different resonant wavelengths were fabricated using an 800 nm femtosecond pulsed laser. The proposed fiber laser incorporates first-order FBGs with the periods of 538, 542, and 547 nm. The femtosecond laser was propagated through polyimide coating and cladding and was focused onto the fiber core by a 63× oil lens, while FBGs were inscribed with the use of a point-by-point method to generate resonant wavelengths at 1555.3, 1569.2, and 1583.1 nm. When the FBGs were used as wavelength selectors, a lasing threshold of 85 mW was obtained, and switchable lasing with stable single- and dual-wavelength outputs was achieved based on the adjustment of a polarization controller. Concerning the switchable single-wavelength lasing, the signal-to-noise ratio was greater than 37.23 dB, and the 3 dB linewidth was less than 0.09 nm. The respective power fluctuation measurements were less than 0.22 and 0.68 dB for the single- and dual-wavelength lasers at 26 °C over a scan time of 30 min.
关键词： Erbium-doped fiber laser,Femtosecond laser,Point-by-point wavelength generation method,Fiber Bragg grating
更新于2025-09-19 17:13:59
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Embedding optical Fiber Bragg Grating (FBG) sensors in 3D printed casings
摘要： This paper aims to numerical and experimentally study and propose Fiber Bragg Grating (FBG) sensors embedded in 3D printed casings. 3D printed casings offer design freedom, enabling strain measurement of structural systems with complex configuration, and, at low cost due to its easiness to manufacture. The casings were first numerically modeled using a commercial finite element software. After the casing was conceptualized to the user needs, they were printed and introduced in two different applications. Assessing the behavior of 3D printed casings in realistic applications has been explored only by few authors, which is the novelty introduced herein. In both applications, the casings’ behavior was analyzed numerical and experimentally. The experimental results were compared with electrical strain gauges. As expected from the numerical analysis results, a calibration factor was determined to accurately predict strain using the embedded FBG sensors. A comprehensive discussion is presented on the topic of calibration factors defined numerical and experimentally.
关键词： Fiber Bragg Grating,3D printing,Casing
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - MEMS-Based Tunable Single-Passband Microwave Photonic Filter
摘要： Single-passband microwave photonic filters have significant advantages such as wide tuning range and high reconfigurability making them attractive photonic subsystems for modern telecommunication systems. However, implementation of such a reconfigurable subsystem requires compact, reliable and low cost tuning mechanism. We report a novel Microelectromechanical Systems (MEMS)-based tunable single-passband microwave photonic filter that uses a chirped fiber Bragg grating as a dispersive element, instead of the conventional single mode optical fiber cable. The tunability is accomplished using a MEMS interferometer implemented by inserting a cleaved single mode fiber in front of a gold-platted micromirror fabricated by Deep Reactive Ion Etching (DRIE) on a Silicon On Insulator (SOI) wafer. The filter is tuned by changing the length between the fiber end and the mirror (ΔL).
关键词： microwave photonic filter,chirped fiber Bragg grating,MEMS,single-passband,tunable,MEMS interferometer
更新于2025-09-19 17:13:59
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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Laser ablation in biliary tree: analysis of the intraductal and superficial thermal effects during the treatment
摘要： The treatment of choice for the unresectable cholangiocarcinoma is based on biliary decompression procedures. Despite stent placement is the standard of care, it is related to well-known complications. Hence, alternative techniques were proposed. Ideally, they should guarantee an adequate intraductal disobstruction, without injuring the surrounding tissues. This pre-clinical study aims to investigate the thermal effects of the laser ablation (LA) in the biliary tree, in terms of intraductal and surrounding tissue temperature achieved with different laser settings. The common bile ducts (in their upper and lower portions) of two pigs were ablated for 6 minutes with a diode laser at 3 W and 5 W. A custom-made laser applicator was used to obtain a circumferential ablation within the ducts. The intraductal temperature (Tid) was monitored by means of a fiber Bragg grating (FBG) sensor, while an infrared thermal camera monitored the T distribution in the surrounding tissues (Tsup). A maximum T difference of 65 °C and 57 °C was evidenced between the two power settings for the Tid measured in the upper and lower ducts, respectively. The mean difference between Tid and the averaged Tsup values was evaluated. At 5 W, a difference of 37±3 °C and 44±10 °C were obtained for the upper and lower ducts, respectively. At 3 W, a T difference of 2±1 °C was obtained for the upper biliary duct, while a difference of 8±1 °C was documented for the lower duct. Based on the results obtained in this preliminary study, the possibility to equip the laser probe with temperature sensor can improve the control and the safety of the procedure; this solution will guarantee the monitoring of the treatment while preserving the lumen and the surrounding structures.
关键词： thermal effects,fiber Bragg grating,biliary tree,cholangiocarcinoma,infrared thermal camera,laser ablation
更新于2025-09-19 17:13:59