- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
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
-
Start current and growth rate in Smith–Purcell free-electron laser with dielectric-loaded cylindrical grating
摘要： We present an analytic theory for Smith–Purcell device in which a cylindrical metal–dielectric grating was derived by an annular electron beam propagating along the grating axis. A dispersion relation is obtained for azimuthally symmetric modes. Also, the first-order and second-order growth rates of the modes which are in phase with the beam are compared. It is shown that the second-order growth rate gives a more accurate description of beam–wave interaction for beams with larger thicknesses, as well as grating slots, with smaller depths and greater lengths. The start current for BWO operation of the SP-FEL is presented too. The importance of the minimum value of start current is that above it, the SP-FEL will operate as an oscillator, even in the absence of external feedback. In this case, the group velocity of the synchronous evanescent wave is negative, while the electron beam travels in the forward direction. It is shown in this paper that the dielectric and grating parameters affect the value of start current. So, by changing these parameters, the minimum value for the start current can be obtained.
关键词： Smith–Purcell FEL,Beam–wave interaction,Cylindrical grating,Growth rate,Dielectric,Start current
更新于2025-09-11 14:15:04
-
[IEEE 2018 IEEE International Instrumentation and Measurement Technology Conference (I2MTC ) - Houston, TX, USA (2018.5.14-2018.5.17)] 2018 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) - Temperature compensation method for FBG-based current sensors for transmission lines
摘要： A method to compensate the temperature influence on electrical current sensors based on fiber Bragg gratings (FBG) is presented in this paper. The operating principle of the method is the employment of a second fiber Bragg grating in the measurement system, called fixed filter, in order to interrogate the output signal from the sensing grating. Once both gratings have been attached to Terfenol-D rods close to each other and subjected to the same temperature variations inside a protective cover, the separation of magnetostrictive strain from the one related to temperature in the output signal can be obtained.
关键词： magnetostrictive strain,sensing grating,fiber Bragg gratings,Current sensors,Terfenol-D,fixed filter
更新于2025-09-11 14:15:04
-
[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
-
Analysis and Design of Closed-loop Detection Technique for Micro-grating Accelerometer
摘要： A novel control method with closed-loop Pound-Drever-Hall (PDH) modulation technology is proposed to optimize the linearity and detection accuracy of micro-grating accelerometer in practical application. The closed-loop error is modulated to a high frequency for eliminating the direct current (DC) component of the interference intensity and stray light disturbance. After phase sensitive detector (PSD) and filter of demodulation, the closed-loop error signal is obtained with high signal to noise ratio (SNR). Based on the principle of designed modulation and demodulation method, the dynamic model of closed-loop micro-grating accelerometer is established considering the nonlinear interference effect, optical intensity fluctuation and unavoidable noise. Then, a robust control algorithm is designed to optimize the performance of micro-grating accelerometer. The experimental results demonstrate that the micro-grating accelerometer has linearity within 0.35% and the bias stability 0.2mg, which validate the effectiveness and usefulness of the proposed closed-loop detection scheme.
关键词： control,closed-loop detection,micro-grating accelerometer,signal process
更新于2025-09-11 14:15:04
-
[IEEE 2017 IEEE Workshop on Recent Advances in Photonics (WRAP) - Hyderabad (2017.12.18-2017.12.19)] 2017 IEEE Workshop on Recent Advances in Photonics (WRAP) - Asymmetric-Pulse Shaping Technique Using Fiber Bragg Grating
摘要： We report a novel optical pulse shaping technique for generating a reverse sawtooth pulse from an optical gaussian pulse using a linearly chirped fiber Bragg grating. We have carried out simulations with gaussian pulses of order 2, 4 and 8 and the results show that asymmetry of the reflected pulse increases with the order of input gaussian pulse.
关键词： Fiber Bragg grating,Reverse sawtooth,Pulse shaping
更新于2025-09-11 14:15:04
-
Characterisation of silicon fibre Bragg grating in near-infrared band for strain and temperature sensing
摘要： Fibre Bragg grating inscription in the crystalline silicon (Si)-core fibre is described using visible light femtosecond laser pulses. The femtosecond pulses at 517 nm propagate through the transparent silica glass cladding and are fully absorbed by the Si core generating locally high temperatures and stress fields in forming the grating periods. The Si FBGs were characterised in reflection, calibrated for a first time as strain and temperature sensors and compared with that of FBGs inscribed in standard silica fibres.
关键词： temperature sensing,femtosecond laser inscription,silicon fibre Bragg grating,near-infrared band,strain sensing
更新于2025-09-11 14:15:04
-
[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Integrated Microphotonic Tuneable Delay Lines for Beam Steering in Phased Array Antennas
摘要： Beam steering in phased array antennas for some demanding terrestrial and space applications needs ultra-wide band true-time tunable delay lines preventing the beam squint phenomenon. Recent advances in the field of integrated microphotonics have allowed the demonstration of compact chip-scale delay lines with fast and low-power tuning mechanisms. For the tuning, several approaches have been theoretically and experimentally investigated and among them, very promising results have been obtained by using graphene in resonant delay lines based on the slow light effect. In this paper, after a brief review on resonant microphotonic tunable delay lines, some selected recent results on an ultra-compact graphene-based optical delay line including a silicon Bragg grating, are proposed.
关键词： optical delay line,photonic crystal,Bragg grating,graphene,microphotonics
更新于2025-09-10 09:29:36
-
[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Fabrication of Doubly-Corrugated Zero-Contrast-Grating for Broadband Pixelated Filtering in the Mid-IR Range
摘要： Zero-contrast grating filters (ZCG) car be used to implement efficient bandpass transmission filter with narrow bandwidths of a few nanometers. In a precedent article [1], we have illustrated the validity of the ZCG approach for the mid-IR range using germanium and calcium fluoride, as well as the possibility to increase both the bandwidth and the angular acceptance of such filters by a decade or more using a double corrugation scheme for the grating. However, when it comes to fabricating such devices, conventional semiconductor methods cannot be straightforwardly applied because of the specific requirements of the infrared materials used. Adapting specific methods of the semiconductor industry, we manage to fabricate such devices. A first optical characterization is performed.
关键词： guided-mode resonances,sub-wavelength grating,infrared,bandpass filters,fabrication
更新于2025-09-10 09:29:36
-
An optical soft-sensor based shape sensing using a bio-inspired pattern recognition technique to realise fly-by-feel capability for intelligent aircraft operation
摘要： Information regarding deformations in large and complex systems is necessary in the prediction of structural failures caused by un-natural flexural occurrences. Sensing systems which are used to predict shapes, in order to develop a global surface picture require high precision and lower time lag. In this work, a unique bio-inspired training mechanism for support vector regression is presented for shape sensing in structures mounted with Fiber Bragg Gratings. Experimental validation was carried out on a simply supported beam, loaded at different positions and an aircraft wing model for different types of bending. The resulting deflections at specified locations along the length of the beam and on both surfaces of the wing were interpreted from the wavelength shifts of the corresponding Fiber Bragg Gratings through the specially modified Support Vector Regression. The method has shown high accuracy, low computational requirements and enhanced prediction times. The proposed bio-inspired training method has also been compared with two conventional training methodologies.
关键词： Fiber Bragg Grating,Decoding variable,Shape sensing,optical soft-sensor,Bio-inspired multi-target single model,Support vector regression
更新于2025-09-10 09:29:36