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Switchable multi-wavelength thulium-doped fiber laser employing a polarization-maintaining sampled fiber Bragg grating
摘要： A continuous wave, switchable multi-wavelength, thulium-doped fiber laser (TDFL) with a polarization-maintaining sampled fiber Bragg grating (PM-SFBG) is proposed and demonstrated for the first time. A length of 150 m highly-nonlinear fiber (HNLF) was used to introduce the four-wave mixing effect for the efficient suppression of the wavelength competition existing in the gain medium of thulium-doped fiber. By adjusting the state of polarization (SOP) of light in the laser cavity, two six-wavelength operations at two orthogonal SOPs and a ten-wavelength operation were obtained. When the TDFL ran at the six-wavelength operation mode with a pump power of 4.11 W, there were at least four lasing wavelengths with an optical signal-to-noise ratio (OSNR) higher than 30 dB, and when it ran at the ten-wavelength operation mode with a pump power of 4.60 W, there were nine lasing wavelengths with an OSNR higher than 30 dB. Regardless of the operation mode, the TDFL exhibited high stability.
关键词： sampled fiber Bragg grating,thulium-doped fiber laser,multi-wavelength
更新于2025-09-11 14:15:04
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Tunable single-longitudinal-mode fiber laser based on a chirped fiber Bragg grating
摘要： In this paper, a tunable single-longitudinal-mode (SLM) fiber laser based on a chirped fiber Bragg grating (CFBG) is proposed and experimentally demonstrated. Multi-sub-cavities formed by a single CFBG inserted inside the laser loop greatly increase the longitudinal mode spacing so that SLM operation can be obtained. The SLM laser output can be tuned in a wide wavelength range from 1535 to 1565 nm by simply adjusting the central wavelength of a tunable optical band-pass filter (TOBF). A side-mode suppression ratio of larger than 50 dB and a linewidth of less than 8.5 kHz have been respectively achieved.
关键词： Single-longitudinal-mode (SLM),Fiber laser,Chirped fiber Bragg grating (CFBG)
更新于2025-09-11 14:15:04
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[IEEE 2019 International Topical Meeting on Microwave Photonics (MWP) - Ottawa, ON, Canada (2019.10.7-2019.10.10)] 2019 International Topical Meeting on Microwave Photonics (MWP) - Nonuniform Microwave Photonic Delay-Line Filter For Optical Sensor Network Interrogation
摘要： We propose a new design of nonuniform spaced microwave photonic delay-line filter based generic optical fiber sensors interrogation platform. Both the amplitude and phase response of the microwave filter are used to demodulate optical sensors. Therefore, a large sensor network with different types of optical sensors can be interrogated simultaneously. The concept of this new microwave photonics enabled interrogation approach is presented and verified by simulations where four different types of optical sensors are simultaneously interrogated via inverse Fourier transform of filter frequency response.
关键词： time delay,fiber Bragg grating,microwave photonics,finite impulse response,Fourier transform,optical sensors
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Optical Sensor Behavior Prediction using LSTM Neural Network
摘要： Optical fiber-based-sensors proved capable of enduring various harsh environments. Long-short-term memory (LSTM) neural-networks are often used for datasets with long- dependences. Here, rare FBG measurements collected from a neutron reactor core were used to build a neural-network capable of predicting the future events inside the reactor.
关键词： Fiber Bragg grating,nuclear reactor core measurements,long-short-term memory,recurrent neural networks
更新于2025-09-11 14:15:04
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Optical Fiber-Based Sensing, Measuring, and Implementation Methods for Slope Deformation Monitoring: A Review
摘要： Slope instabilities are a common occurrence in hilly areas, mine, and dam region, which bring a grave threat to the safety of transportation business and human life. The effective slope monitoring methods and instruments can provide information on the current deformation and historical trends, which is important scientific information for researchers to analyze slope stability and provide a timely warning to the public. Optical fiber sensors (OFS) have attracted many researchers to explore due to their have unique advantages in comparison with conventional electronic based sensing technologies, including immunity to electromagnetic interference, remote transmission, easy integration and high sensitivity. This paper presents an overview of the latest development and application of OFS based slope deformation monitoring from two aspects: 1) Fiber Bragg grating (FBG) based sensing and monitoring technology; 2) Distributed optical fiber sensors (DOFS) Brillouin Optical Time Domain Reflectometry (BOTDR) and Brillouin Optical Time Domain Analysis (BOTDA) for slope monitoring. Meanwhile, current challenges in implementing the OFS-based slope monitoring technology are discussed.
关键词： Optical fiber sensors,Distributed optical fiber sensors,Fiber Bragg grating,Slope deformation monitoring
更新于2025-09-11 14:15:04
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Femtosecond Laser Inscribed Sapphire Fiber Bragg Grating for High Temperature and Strain Sensing
摘要： In this paper, a sapphire fiber Bragg grating (SFBG) is fabricated by femtosecond (fs) laser line-by-line scanning method. A third-order fiber Bragg grating is obtained in a single crystal sapphire fiber with a diameter of 60 μm. Compared to the SFBG written by point-by-point method, the SFBG written by the line-by-line method has a higher reflectivity and grating with about 15% reflectivity is achieved when the track length is about 40 μm. The temperature sensing characteristics of this SFBG from room temperature to 1600°C are studied, and the temperature sensitivity of SFBG is 34.96 pm/°C from 1000°C to 1600°C. The strain characteristics are also tested at the temperature of 26°C, 500°C, 1000°C and 1600°C, and the strain sensitivities are 1.42 pm/με, 1.42pm/με, 1.44 pm/με and 1.45 pm/με, respectively. These characteristics show that this SFBG has potential applications in harsh environment structural health monitoring.
关键词： structural health monitoring,femtosecond laser,line-by-line scanning,Sapphire fiber Bragg grating
更新于2025-09-11 14:15:04
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SCADE: Simultaneous Sensor Calibration and Deformation Estimation of FBG-Equipped Unmodeled Continuum Manipulators
摘要： In this article, we present a novel stochastic algorithm called simultaneous sensor calibration and deformation estimation (SCADE) to address the problem of modeling deformation behavior of a generic continuum manipulator (CM) in free and obstructed environments. In SCADE, using a novel mathematical formulation, we introduce a priori model-independent ?ltering algorithm to fuse the continuous and inaccurate measurements of an embedded sensor (e.g., magnetic or piezoelectric sensors) with an intermittent but accurate data of an external imaging system (e.g., optical trackers or cameras). The main motivation of this article is the crucial need of obtaining an accurate shape/position estimation of a CM utilized in a surgical intervention. In these robotic procedures, the CM is typically equipped with an embedded sensing unit (ESU) while an external imaging modality (e.g., ultrasound or a ?uoroscopy machine) is also available in the surgical site. To evaluate the ef?cacy of the SCADE algorithm, we performed two different sets of experiments in free and obstructed environments. In these experiments, we utilized a CM speci?cally designed for orthopedic interventions equipped with an inaccurate ?ber Bragg grating (FBG) ESU and an overhead camera. The experimental results demonstrated the successful performance of the SCADE algorithm in simultaneous estimation of unknown deformation behavior of the utilized unmodeled CM together with realizing the time-varying drift of the poor-calibrated FBG sensing unit. Moreover, the results showed the phenomenal out-performance of the SCADE algorithm in estimation of the CM’s tip position as compared to FBG-based position estimations.
关键词： Continuum manipulators (CMs),sensor fusion,?ber Bragg grating (FBG) sensor,medical robots and systems
更新于2025-09-11 14:15:04
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Label-free detection of ambient refractive index based on plasmonic Bragg gratings embedded resonator cavity sensor
摘要： In this work, we incorporated Bragg gratings in the standard ring resonator design in order to enhance the sensitivity of the refractive index sensor. The transmission spectrum and electric field distribution of the device are simulated using the finite element method (FEM). The numerical simulation results obtained from the transmission spectrum are used to examine the sensing characteristics of the structure. The size of the grating teeth has a significant effect on the intensification of surface plasmons which in turns enhances the interaction between the ambient medium and the light. Bragg grating embedded resonator cavity design has the best sensitivity, FOM and Q-factor of 1680 nm/RIU, 48 and 48.4, respectively which is much higher than several previously reported values.
关键词： metal-insulator-metal waveguide,Plasmonics,Bragg grating,Refractive index sensor,finite element method
更新于2025-09-11 14:15:04
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Effect of Temperature and Gamma-Ray Irradiation on Optical Characteristics of Fiber Bragg Grating Inscribed Radiation-Resistant Optical Fiber
摘要： A new radiation-hard germano-silicate glass optical fiber with a pure silica glass buffer and a boron-doped silica glass inner cladding was fabricated for temperature sensor application based on the fiber Bragg grating (FBG) under γ-ray irradiation environment. The temperature dependences of optical attenuation at 1550.5 nm and Bragg reflection wavelength shift from 18 ℃ to 40 ℃ before the γ-ray irradiation were about 4.57×10–4 dB/℃ and 5.48 pm/℃, respectively. The radiation-induced optical attenuation at 1550.5 nm and the radiation-induced Bragg reflection wavelength shift under the γ-ray irradiation with the total dose of 22.85 kGy at 35 ℃ were about 0.03 dB/m and 0.12 nm, respectively, with the γ-ray irradiation sensitivity of 5.25×10–3 pm/Gy. The temperature and the γ-ray irradiation dependence of optical attenuation at 1550.5 nm in the FBG written fiber with boron-doped silica glass inner cladding were about 6 times and 4 times lower than that in the FBG written fiber without boron-doped silica glass inner cladding under a temperature change from 18 ℃ to 40 ℃ and the γ-ray irradiation with the total dose of 22.85 kGy at 35 ℃, respectively. Furthermore, the effect of temperature increase on the Bragg reflection wavelength of the FBG written fiber with boron-doped silica inner cladding was much larger about 1000 times than that of the γ-ray irradiation. However, no influence on the reflection power of the Bragg wavelengths and the full width at half maximum (FWHM) bandwidth under temperature and the γ-ray irradiation change was found. Also, after the γ-ray irradiation with the dose of 22.85 kGy, no significant change in the refractive index was found but the residual stresses developed in the fiber were slightly relaxed or retained.
关键词： Optical fiber,radiation-induced attenuation,fiber Bragg grating,temperature sensor,radiation resistance
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA, USA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - Dynamics of Colliding Solitons in a Coupler with Separated Nonuniform Bragg Grating and Nonlinearity
摘要： In this paper we present the systematic analysis of the collisions of counter-propagating gap solitons in a linearly coupled dual-core system where one core has only Kerr nonlinearity and the other core is linear which contains a nonuniform Bragg grating with dispersive reflectivity.
关键词： dispersive reflectivity,Gap soliton,Bragg grating
更新于2025-09-11 14:15:04