- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Simultaneous Measurement of Axial Strain, Bending and Torsion with a Single Fiber Bragg Grating in CYTOP Fiber
摘要： This paper presents the development of a 3-D displacement sensor based on one fiber Bragg grating (FBG). In order to obtain higher sensitivity and dynamic range, the FBG is inscribed in low-loss, multimode, cyclic transparent amorphous fluoropolymers (CYTOP) using the direct-write, plane-by-plane femtosecond laser inscription method. The proposed sensor is based on the influence of each displacement condition, namely axial strain, torsion and bending on the FBG reflection spectrum. Such influence is analyzed with respect to the FBG wavelength shift, reflectivity and full width half maximum (FWHM). The operation principle and theoretical background of the proposed approach is numerically analyzed by means of finite element analysis for the strain along the grating length and coupled-mode theory with a modified transfer matrix formulation for the FBG spectrum. The sensor is experimentally characterized and validated in which the results show good agreement between the applied axial strain, bending and torsion with relative errors below 5.5%. Thus, the proposed sensor is an interesting alternative for measuring displacements in 3-D applications such as movement analysis and the instrumentation of novel soft robots.
关键词： Polymer optical fiber,3-D displacement,fiber Bragg gratings,CYTOP
更新于2025-09-09 09:28:46
-
High-Sensitivity Temperature Sensor Based on Polarization Maintaining Fiber Sagnac Loop
摘要： A high-sensitivity all-fiber temperature sensor based on a Sagnac interferometer is demonstrated by splicing a section of polarization maintaining fiber (PMF) between two sections of standard single mode fibers (SMFs). In this sensor, the SMF-PMF-SMF structure in the Sagnac loop is bent into a circle to enhance the sensitivity. The length and curvature of the PMF in the loop are investigated and can be optimized to further increase the temperature sensitivity of the sensor. Results show that the radius of the circle has an important effect upon temperature sensitivity due to the bend-induced birefringence variation of the PMF. The SMF-PMF-SMF structure bent into a circle with a radius of 30 mm exhibits a high-sensitivity temperature of 1.73 nm/℃. The sensor is provided with the advantages of easy fabrication, low-insertion loss, and high sensitivity, which may find potential applications in the field of high precision temperature measurement.
关键词： polarization maintaining fiber,Sagnac loop,Optical fiber sensor,temperature sensor
更新于2025-09-09 09:28:46
-
[IEEE 2018 IEEE 20th International Conference on e-Health Networking, Applications and Services (Healthcom) - Ostrava, Czech Republic (2018.9.17-2018.9.20)] 2018 IEEE 20th International Conference on e-Health Networking, Applications and Services (Healthcom) - Design of hybrid EPON network with fiber-optic breath sensors
摘要： Optical fiber sensors are nowadays rapidly growing in the field of biomedical applications. It is possible to measure various variables, such as vital function, perform analysis of an analyte or observe bioluminescence. Specialized measurement using fiber optic sensors is the breath monitoring. For example, this system can be embedded into a bed for, or it can be a mobile device. Due to the passivity at the place of measurement and the use of non-magnetic materials in probe design, this solution is particularly interesting in applications where the environment is disturbed by the strong magnetic field such as in magnetic resonance imaging. The passivity of the sensor and operation over to long distance led to the idea of integration of sensors directly into the passive optical network. The design of coexistence of optic-fiber biosensors and PON is the primary aim of this publication. The proposed simulations and laboratory measurements point to problems that cause sensor integration into the network. As a result, methods for integrating sensors without compromising the communication part of the network are presented.
关键词： biosensors,optical fiber,sensors,passive optical network,breath monitoring,PON
更新于2025-09-09 09:28:46
-
An Empirical Study of In-Fiber Mach-Zehnder Interferometer’s Nonlinear Temperature Response
摘要： In this paper, we explore an empirical model capable to describe the nonlinear temperature response of in-fiber Mach–Zehnder interferometers (MZI). This model describes the nonlinear and linear response ranges with the same accuracy. It shows how the refractive index of the silica and the surroundings, including their thermo-optic coefficients, contribute to the temperature sensitivity (TS). It is also capable of predicting maxima and minima values for the TS, as well the conditions for the linear response to the temperature. Five different surroundings have been tested: air, water, ethanol, turpentine, and kerosene, in a temperature ranging from 20°C to 45°C. The resulting experimental TS values have ranged from 50 pm/°C to 1000 pm/°C. At 20°C, the calculated theoretical minimum and maximum TS were 45 pm/°C and 5377 pm/°C. We also show that this model can be applied to calculate temperature from wavelength measurements with arbitrary precision, as well as it can be used to identify substances through wavelength and temperature measurements.
关键词： Mach-Zehnder interferometer,cascaded long period grating,tunable temperature sensitivity,nonlinear response,Optical fiber sensor
更新于2025-09-09 09:28:46
-
In?Vivo Real-Time Discrimination Among Glioma, Infiltration Zone, and Normal Brain Tissue via Autofluorescence Technology
摘要： BACKGROUND: Surgery is the first-line therapy for glioblastoma. There is evidence that extent of resection is significantly associated with patient survival. Unfortunately, optimal surgical resection is usually limited because of the difficulty in discriminating tumor-infiltrated region and normal brain tissue. This study aimed to develop a tool to distinguish between infiltration zone and normal tissue in real time during glioma surgery. METHODS: In an in vivo study, C6 glioma cells were implanted into the left cerebral hemispheres of 6 rats to mimic tumorigenesis. A newly designed optical fiber-embedded needle probe was used to measure the autofluorescence of both cerebral hemispheres at various depths 5 days after the implantation. These rats were then sacrificed, and both cerebral hemispheres were removed for histopathologic analysis. RESULTS: Comparative analyses of corresponding areas by histopathology and autofluorescence revealed highly significant (P < 0.001) differences among the normal tissue, infiltration zone, tumors, and the contralateral cerebral hemispheres. The area of the receiver operating characteristic curve was 0.978, and the sensitivity and specificity of tumor delineation were 93.9% and 94.4%, respectively. CONCLUSIONS: The newly designed in vivo fiber-optic probe can distinguish tumor-infiltration zones from normal brain tissue in this in vivo study. Therefore, it may help neurosurgeons to increase extent of resection without damaging normal brain tissue and thus potentially improve the patients’ survival and quality of life.
关键词： Glioblastoma,Optical-fiber,Infiltration,Auto-fluorescence
更新于2025-09-09 09:28:46
-
Infiltrated Photonic Crystal Fibers for Sensing Applications
摘要： Photonic crystal ?bers (PCFs) are a special class of optical ?bers with a periodic arrangement of microstructured holes located in the ?ber’s cladding. Light con?nement is achieved by means of either index-guiding, or the photonic bandgap effect in a low-index core. Ever since PCFs were ?rst demonstrated in 1995, their special characteristics, such as potentially high birefringence, very small or high nonlinearity, low propagation losses, and controllable dispersion parameters, have rendered them unique for many applications, such as sensors, high-power pulse transmission, and biomedical studies. When the holes of PCFs are ?lled with solids, liquids or gases, unprecedented opportunities for applications emerge. These include, but are not limited in, supercontinuum generation, propulsion of atoms through a hollow ?ber core, ?ber-loaded Bose–Einstein condensates, as well as enhanced sensing and measurement devices. For this reason, in?ltrated PCF have been the focus of intensive research in recent years. In this review, the fundamentals and fabrication of PCF in?ltrated with different materials are discussed. In addition, potential applications of in?ltrated PCF sensors are reviewed, identifying the challenges and limitations to scale up and commercialize this novel technology.
关键词： optical fiber sensors,photonic crystal fibers,optofluidics,plasmonic sensors,liquid crystals
更新于2025-09-09 09:28:46
-
Events detection and recognition by the fiber vibration system based on power spectrum estimation
摘要： One of the important successes of optical fiber sensor established for the security system is the detection and the recognition of any type of events. The performance parameters (event recognition, event detection position, and time of detection) are unavoidable and describe the validity of any perimeter detection system. An event recognition is any signal detected within the protected area, and it is related to a non-intrusion event and an intrusion event. To achieve the detection and the recognition events at the real time, an effective two-level vibration recognition method and a technique are proposed and presented in this article. The signal characteristics (short-term energy and short-time over-threshold) have been used and compared to the dynamic threshold to judge the type of event. Then the extraction of the power distribution features on the frequency domain through power spectral estimation on the suspected intrusion signal samples is carried out and finally combined with the time-domain characteristics as feature vector through Support Vector Machine to determine the efficiency and effectiveness of the proposed vibration recognition method. The experimental simulation results show that the proposed method is effective and reliable. With collected data, it can detect and recognize the type of event in real time.
关键词： Support Vector Machine,event detection and recognition,power spectral estimation,Optical fiber sensor,dynamic threshold,short-time over-threshold,short-term energy
更新于2025-09-09 09:28:46
-
[IEEE 2018 IFIP/IEEE International Conference on Performance Evaluation and Modeling in Wired and Wireless Networks (PEMWN) - Toulouse, France (2018.9.26-2018.9.28)] 2018 IFIP/IEEE International Conference on Performance Evaluation and Modeling in Wired and Wireless Networks (PEMWN) - SI-POF Transmission with OFDM and Sub-carrier Pairwise Coding
摘要： In this study, data transmission over step-index plastic optical fiber (SI-POF) is demonstrated using orthogonal frequency division multiplexing (OFDM) scheme with sub-carrier pairwise coding (PWC). To investigate the performance of OFDM with PWC, a simulation study is implemented with QPSK and 16-QAM format using the Gaussian theoretical frequency response for a 60 m SI-POF channel. For a data rate of 200 Mbps with QPSK-OFDM, the study shows that compared to equalization, PWC offers about 1.5 dB improvement at a bit-error-rate (BER) of 10-3. An experiment is then set-up with a 60 m SI-POF that uses an eye-safe resonant cavity light emitting diode (RC-LED) as the optical source. The experiment shows that at a bit rate of 200 Mbps with QPSK-OFDM, PWC offers a 1.82 dB improvement in SNR at a BER of 10-3. For the same data rate with 16-QAM-OFDM, PWC offers about 1.1 dB Q2-factor improvement for a modulation index of 0.8. The study therefore shows that PWC improves the BER performance of an SI-POF link that uses OFDM.
关键词： pairwise coding (PWC),plastic optical fiber (POF),equalization,Orthogonal frequency division modulation (OFDM)
更新于2025-09-09 09:28:46
-
High dispersion four-mode fiber for mode-division multiplexing systems
摘要： This paper presents a novel dispersions equalization technique for multilayer core four-mode fiber using LP mode-matrix method. Each of the core ring radius of the alternating center-high (CH) and center-low (CL) index profile was optimized to a specific thickness value. The core ring radius varied in each case to determine the optimized thickness (OPT) for the dispersions equalization. The OPT of the center high index core fiber (CH) denoted by R1, R2, and R3 were found to be 4.25 μm, 2.6 μm, and 2.3 μm, respectively. Similarly, an OPT of the center low index core fiber (CL) which was denoted by X1, X2, X3, and X4 was found to be 2.0 μm, 3.0 μm, 4.20 μm and 1.60 μm, respectively. At 1.55 μm wavelength, these values were used to model the two fibers to achieve an equalized modal dispersion. It is the first time, to our knowledge, a core-ring radius of a CH, and CL index profile varied to a certain OPT value to achieve dispersion equalization. Fabrication challenges were also discussed in this paper.
关键词： mode division multiplexing,Optical fiber,dispersion tolerance,dispersion
更新于2025-09-09 09:28:46
-
Hybrid structure Mach–Zehnder interferometer based on silica and fluorinated polyimide microfibers for temperature or salinity sensing in seawater
摘要： An all-fiber hybrid structure Mach-Zehnder interferometer (MZI) based on silica fiber and fluorinated polyimide microfiber (FPMF) for temperature or salinity sensing in seawater is proposed. Theoretically, transmission characteristic and sensing sensitivity of the MZI are derived for this kind of hybrid structure, and typical interference spectrum is observed around optical communication band. Experimentally, by tracking the shift of interference peaks, temperature and salinity sensing are demonstrated with sensitivities of about 140pm/°C and 64pm/‰, respectively, which are much higher than those of existing fiber Bragg gratings and microfiber knot resonators. In addition, dependences of sensitivity on sensor parameters, such as fiber diameter and fiber lengths, are also investigated. Unlike the other microfiber based sensors that higher sensitivity usually comes from the thinner fiber, sensors demonstrated here show that sensitivities can be tuned by changing the path-length difference of the two arms, which greatly decreases the difficulty in component fabrications. Temperature or salinity sensor demonstrated here show advantages of simple fabrication, low cost, tunable sensitivity and dynamic range, relatively high sensitivity and compatible with standard fiber optics system, which may have potential applications in developing low cost and compact size optical sensors in ocean or other liquid surroundings.
关键词： salinity,temperature,hybrid structure,microfiber,Optical fiber sensor,Mach-Zehnder interferometer
更新于2025-09-09 09:28:46