A new type of Bragg fibers, i.e. hollow-core cobweb-structured optical fibers, which can be used to the low-loss transmis- sion from visible to near infrared region (0.65 μm-1.55 μm), terahertz wave (200 μm-480 μm...A new type of Bragg fibers, i.e. hollow-core cobweb-structured optical fibers, which can be used to the low-loss transmis- sion from visible to near infrared region (0.65 μm-1.55 μm), terahertz wave (200 μm-480 μm) and circular-polariza- tion-maintaining single-mode transmission are investigated. Results show that the hollow-core cobweb-structured fibers have less loss than other hollow-core Bragg fibers. The fibers can be constituted by using the plastics or glasses with large absorption losses.展开更多
We propose a silica-core dispersion-decreasing Bragg fiber （DDBF） of mode effective area as large as 55 μm^2 for supercontinuum （SO） generation at the pump wavelength of 1060 nm. Using a fast and simple matrix me...We propose a silica-core dispersion-decreasing Bragg fiber （DDBF） of mode effective area as large as 55 μm^2 for supercontinuum （SO） generation at the pump wavelength of 1060 nm. Using a fast and simple matrix method to model propagation in the DDBF,we have presented a general criterion to obtain the shortest length of the DDBF that would result in a broad SO spectrum. The proposed DDBF design should be amenable for reproducible fabrication through the well-developed MCVD fiber manufacturing technology and the concept has potential for realization as a practical device.展开更多
In this presentation the feasibility and capability of fiber Bragg gratings （FBG） employed in bridge health monitoring are demonstrated on a real bridge. FBG＇ s wavelength shift depending on strain variance has bee...In this presentation the feasibility and capability of fiber Bragg gratings （FBG） employed in bridge health monitoring are demonstrated on a real bridge. FBG＇ s wavelength shift depending on strain variance has been tested. The technique of FBG installation on bridges has been developed. 12 FBG strain sensors and 3 temperature sensors have been successfully embedded in the prestressed concrete box girder during the construction of Heilongjiang Hulan River Bridge. The prestressing tension process and quasi-static loading process of the girder were monitored with those sensors before it was installed onto the bridge. After the bridge was completed, the FBG sensors embedded have been utilized to monitor the strain shift of the beam under quasi-static load, traffic load and temperature. The results show that the traffic fluxes, possible tatigue damage and deflection of the bridge can be revealed conveniently through strain measurements with these FBG sensors, which provide key information for structural health diagnosis. The fact that the FBG strain sensors have withstood the ordeal of harsh construction process and lasted for more than one year proves that their durability and stability can satisfy the requirements for bridge health monitoring. It is also shown that the FBG strain sensor is more adaptive to long-term structural health monitoring than the electric resistance strain gauge.展开更多
We investigate the unconventional Landau levels of ultracold fermionic atoms on the two-dimensionalhoneycomb optical lattice subjected to an effective magnetic field,which is created with optical means.In the presence...We investigate the unconventional Landau levels of ultracold fermionic atoms on the two-dimensionalhoneycomb optical lattice subjected to an effective magnetic field,which is created with optical means.In the presenceof the effective magnetic field,the energy spectrum of the unconventional Landau levels is calculated.Furthermore,wepropose to detect the unconventional Landau levels with Bragg scattering techniques.展开更多
Fiber Bragg grating(FBG) is used as a wavelength reference device to calibrate the position of gas absorption peak in the intracavity absorption gas sensor(ICAGS) based on erbium-doped fiberring laser.This system can ...Fiber Bragg grating(FBG) is used as a wavelength reference device to calibrate the position of gas absorption peak in the intracavity absorption gas sensor(ICAGS) based on erbium-doped fiberring laser.This system can detect both the reflectance spectrum of FBGs and absorption spectrum of measured gas during a single wavelength sweeping process by linearly varying the driving voltage of optic filter.The voltages corresponding to center wavelength positions of four FBGs in the spectrum are determined through ...展开更多
This paper deals with an improved bonding approach of surface-bonded fiber Bragg grating (FBG) sensors for airship envelope structural health monitoring (SHM) under the strain transfer theory. A theoretical formula is...This paper deals with an improved bonding approach of surface-bonded fiber Bragg grating (FBG) sensors for airship envelope structural health monitoring (SHM) under the strain transfer theory. A theoretical formula is derived from the proposed model to predict the strain transfer relationship between the airship envelope and fiber core. Then theoretical predictions are validated by numerical analysis using the finite element method (FEM). Finally, on the basis of the theoretical approach and numerical validation, parameters that influence the strain transfer rate from the airship envelope to fiber core and the ratio of effective sensing length are analyzed, and some meaningful conclusions are provided.展开更多
The authors review their recent advances in the development of optical fiber Bragg grating （FBG） sensor technologies. After a brief review of the fiber grating sensors, several newly developed FBG sensors are descri...The authors review their recent advances in the development of optical fiber Bragg grating （FBG） sensor technologies. After a brief review of the fiber grating sensors, several newly developed FBG sensors are described. With the continuous development of fiber materials, microstructures and post-processing technologies, FBG sensors are still creative after the first demonstration of permanent gratings thirty years ago.展开更多
A novel optical microfiber asymmetric Fabry-Perot interferometric （MAFPI） sensor is developed for simultaneous measurement of force and temperature. The MAFPI structure is formed by a weak fiber Bragg grating （FBG...A novel optical microfiber asymmetric Fabry-Perot interferometric （MAFPI） sensor is developed for simultaneous measurement of force and temperature. The MAFPI structure is formed by a weak fiber Bragg grating （FBG）, a section of the microfiber, and a cleaved fiber end surface. The narrowband beam reflected from the low-reflectivity FBG and the broadband beam from the Fresnel reflection interfere lead to its unique sensing performance. The force sensing is performed by detecting the bending-loss induced fringe contrast changes, while the Bragg wavelength shift is employed for temperature measurement. Sensitivities of 9.8pm/℃ and 0.025dB/μN were obtained experimentally for temperature and force measurements, respectively.展开更多
基金the National Natural Science Foundationof China (No. 60577009, 60444003)
文摘A new type of Bragg fibers, i.e. hollow-core cobweb-structured optical fibers, which can be used to the low-loss transmis- sion from visible to near infrared region (0.65 μm-1.55 μm), terahertz wave (200 μm-480 μm) and circular-polariza- tion-maintaining single-mode transmission are investigated. Results show that the hollow-core cobweb-structured fibers have less loss than other hollow-core Bragg fibers. The fibers can be constituted by using the plastics or glasses with large absorption losses.
文摘We propose a silica-core dispersion-decreasing Bragg fiber （DDBF） of mode effective area as large as 55 μm^2 for supercontinuum （SO） generation at the pump wavelength of 1060 nm. Using a fast and simple matrix method to model propagation in the DDBF,we have presented a general criterion to obtain the shortest length of the DDBF that would result in a broad SO spectrum. The proposed DDBF design should be amenable for reproducible fabrication through the well-developed MCVD fiber manufacturing technology and the concept has potential for realization as a practical device.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 10402010).
文摘In this presentation the feasibility and capability of fiber Bragg gratings （FBG） employed in bridge health monitoring are demonstrated on a real bridge. FBG＇ s wavelength shift depending on strain variance has been tested. The technique of FBG installation on bridges has been developed. 12 FBG strain sensors and 3 temperature sensors have been successfully embedded in the prestressed concrete box girder during the construction of Heilongjiang Hulan River Bridge. The prestressing tension process and quasi-static loading process of the girder were monitored with those sensors before it was installed onto the bridge. After the bridge was completed, the FBG sensors embedded have been utilized to monitor the strain shift of the beam under quasi-static load, traffic load and temperature. The results show that the traffic fluxes, possible tatigue damage and deflection of the bridge can be revealed conveniently through strain measurements with these FBG sensors, which provide key information for structural health diagnosis. The fact that the FBG strain sensors have withstood the ordeal of harsh construction process and lasted for more than one year proves that their durability and stability can satisfy the requirements for bridge health monitoring. It is also shown that the FBG strain sensor is more adaptive to long-term structural health monitoring than the electric resistance strain gauge.
基金Supported by the Teaching and Research Foundation for the Outstanding Young Faculty of Southeast University
文摘We investigate the unconventional Landau levels of ultracold fermionic atoms on the two-dimensionalhoneycomb optical lattice subjected to an effective magnetic field,which is created with optical means.In the presenceof the effective magnetic field,the energy spectrum of the unconventional Landau levels is calculated.Furthermore,wepropose to detect the unconventional Landau levels with Bragg scattering techniques.
基金Supported by Major State Basic Research Program of China("973"Program,No.2010CB327800)Research Fund for Doctoral Program of Higher Education of China(No.20090032110053)New Teacher Research Fund for Doctoral Program of Higher Education of China (No.200800561022)
文摘Fiber Bragg grating(FBG) is used as a wavelength reference device to calibrate the position of gas absorption peak in the intracavity absorption gas sensor(ICAGS) based on erbium-doped fiberring laser.This system can detect both the reflectance spectrum of FBGs and absorption spectrum of measured gas during a single wavelength sweeping process by linearly varying the driving voltage of optic filter.The voltages corresponding to center wavelength positions of four FBGs in the spectrum are determined through ...
基金Project (No. 2011AA7052011) supported by the National High-Tech R&D (863) Program of China
文摘This paper deals with an improved bonding approach of surface-bonded fiber Bragg grating (FBG) sensors for airship envelope structural health monitoring (SHM) under the strain transfer theory. A theoretical formula is derived from the proposed model to predict the strain transfer relationship between the airship envelope and fiber core. Then theoretical predictions are validated by numerical analysis using the finite element method (FEM). Finally, on the basis of the theoretical approach and numerical validation, parameters that influence the strain transfer rate from the airship envelope to fiber core and the ratio of effective sensing length are analyzed, and some meaningful conclusions are provided.
文摘The authors review their recent advances in the development of optical fiber Bragg grating （FBG） sensor technologies. After a brief review of the fiber grating sensors, several newly developed FBG sensors are described. With the continuous development of fiber materials, microstructures and post-processing technologies, FBG sensors are still creative after the first demonstration of permanent gratings thirty years ago.
基金This work is supported by the National Natural Science Foundation of China （61107073, 61107072 and 61290312）, Fundamental Research Funds for the Central Universities （ZYGX2011J002）, Research Fund for the Doctoral Program of Higher Education of China （20110185120020）, Program for Changjiang Scholars and Innovative Research Team in University （PCSIRT, IRT1218）, and the 111 Project （B 14039）. Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author（s） and source are credited.
文摘A novel optical microfiber asymmetric Fabry-Perot interferometric （MAFPI） sensor is developed for simultaneous measurement of force and temperature. The MAFPI structure is formed by a weak fiber Bragg grating （FBG）, a section of the microfiber, and a cleaved fiber end surface. The narrowband beam reflected from the low-reflectivity FBG and the broadband beam from the Fresnel reflection interfere lead to its unique sensing performance. The force sensing is performed by detecting the bending-loss induced fringe contrast changes, while the Bragg wavelength shift is employed for temperature measurement. Sensitivities of 9.8pm/℃ and 0.025dB/μN were obtained experimentally for temperature and force measurements, respectively.
