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Yb-doped superfluorescent fiber source with cascaded broad fiber bragg gratings

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Chinese Optics Letters 2003年第3期1卷 131-132页

作者：乔启全刘月英陈柏范薇陈嘉琳林尊琪 National Laboratory on High Power Lasers and Physics Sbanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Shanghai 201800 State Key Laboratory of Transducer Technology Shanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences Shanghai 200050 National Laboratory on High Power Lasers and Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Shanghai 201800

In this paper, the Yb-doped superfluorescent fiber source (SFS) with cascaded broad fiber bragg gratings (FBGs) are reported. The spectral properties of this SFS with cascaded broad FBGs are described and compared with that without cascaded broad FBGs. The experimental results have shown that cascaded broad FBGs can increase the output of some special wave bands.

关键词： Doping (additives) fiber bragg gratings Fluorescence Ytterbium

Response Analysis of Ultrasonic Sensing System Based on fiber bragg gratings of Different Lengths

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Photonic Sensors 2014年第3期4卷 281-288页

作者： Dandan PANG Qingmei SUI School of Control Science and Engineering Shandong University Jinan 250061 China

In recent years, fiber bragg gratings （FBGs） have been widely used in ultrasonic detection for practical structural health monitoring in light of its unique advantages over the conventional sensors. Although FBGs have been successfully tested in ultrasonic inspection, the effect of the grating length on the sensitivity of the FBG ultrasonic sensing system is yet to be analyzed. Hence, using the simulation model, the main influencing factor on the sensitivity of the ultrasonic sensing system with different lengths gratings was first investigated. In the following experiment, the ultrasonic responses of the sensing system with six different lengths FBGs were obtained, respectively. The theoretical analysis and the experimental results would be useful for sensitivity improvement of the FBG-based ultrasonic and acoustic emission sensing system.

关键词： fiber bragg gratings bragg reflectors optical sensing and sensors

Variable Wavelengths fiber bragg gratings Written with A Phase Mask and Four Prisms

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Chinese Journal of Lasers 2002年第5期11卷 28-31页

作者：张以谟李川刘铁根丁胜吕且妮 The Institute of Contemparary Optical Instruments Engineering Tianjin University The Key Laboratory of Optoelectronics Information Science & Technology EMC 天津 300072 The Institute of Contemparary Optical Instruments Engineering Tianjin University The Key Laboratory of Optoelectronics Information Science & Technology，EMC 天津 300072

Using only one diffractive element, the Talbot interferometer provides a robust and inherently stable method for reproducing fiber bragg gratings with variable wavelengths, and reduces the complexity of the fiber grating fabrication system. However, the usable length of the grating is limited by the practical length of the mirrors. This paper presents a phase mask with two fixed prisms and two rotational prisms to inscribe fiber bragg gratings with variable bragg wavelengths. In this system, the fiber bragg grating is inscribed by UV interference stripes of 193 nm derived from two rotational prisms and two fixed prisms, where phase mask is used as a beam splitter of ±1 order diffraction light. It is noteworthy that the tunable phase mask interferometer decreases the demand of the length of prism evidently.

关键词： fiber bragg gratings phase mask UV transmitting silica prism interfering region.

Simultaneously compensating tunable CD and adaptive PMD using two different nonlinearly chirped fiber bragg gratings

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Chinese Optics Letters 2004年第8期2卷 445-448页

作者：于丽张晓光周光涛刘玉敏张建忠席丽霞杨伯君 School of Science Beijing University of Posts and Telecommunications Beijing 100876 School of Science Beijing University of Posts and Telecommunications Beijing 100876xperimental research of simultaneous tunable chromatic dispersion (CD) and adaptive polarization mode dispersion (PMD) compensations in optical fiber communication system was reported. Two different nonlinearly chirped fiber Bragg gratings fabricated through the equivalent chirp technology were adopted in the experiment. One of the gratings was used as CD compensator with a tunable dispersion range from 300 to 600 ps/nm. The other made of photosensitive polarization maintaining fiber was used as a tunable delay line of PMD compensator which provided a varying amount of differential group delay (DGD) from 40 to 110 ps. Our experiment was operated at 10-Gb/s non-return-to-zero (NRZ) system and the results showed that the eye pattern recovery is excellent after both PMD and CD are compensated. Especially the power penalty at a bit error rate (BER) of 10-9 is about 1 dB.

Experimental research of simultaneous tunable chromatic dispersion (CD) and adaptive polarization mode dispersion (PMD) compensations in optical fiber communication system was reported. Two different nonlinearly chirped fiber bragg gratings fabricated through the equivalent chirp technology were adopted in the experiment. One of the gratings was used as CD compensator, with a tunable dispersion range from 300 to 600 ps/nm. The other made of photosensitive polarization maintaining fiber was used as a tunable delay line of PMD compensator, which provided a varying amount of differential group delay (DGD) from 40 to 110 ps. Our experiment was operated at 10-Gb/s non-return-to-zero (NRZ) system and the results showed that the eye pattern recovery is excellent after both PMD and CD are compensated. Especially, the power penalty at a bit error rate (BER) of 10-9 is about 1 dB.

关键词： Bit error rate Electromagnetic dispersion fiber bragg gratings

Theoretical analysis of transmission characteristics for all fiber,multi-cavity Fabry-Perot filters based on fiber bragg gratings

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Science in China(Series F) 2008年第9期51卷 1391-1400页

作者： XU Ou1,2,LU ShaoHua1,2,DONG XiaoWei1,2,LI Bin1,2,NING TiGang1,2 & JIAN ShuiSheng1,2 1 Key Lab of All Optical Network & Advanced Telecommunication Network of EMC,Beijing Jiaotong University,Beijing 100044,China 2 Institute of Lightwave Technology,Beijing Jiaotong University,Beijing 100044,China Key Lab of All Optical Network & Advanced Telecommunication Network of EMC Beijing Jiaotong University Beijing 100044 China Institute of Lightwave Technology Beijing Jiaotong University Beijing 100044 China

The characteristics of transmission spectra for the all fiber, multi-cavity Fabry- Perot （FP） configuration based on fiber bragg gratings （FBG） are theoretically analyzed and modeled. The general transmission matrix function for the structure with any number of cavities is derived, and explicit expression of the power trans- mission coefficient for symmetrical two-cavity FP is presented. The general condi- tions for flat-top single resonant peak at the central wavelength in FBG stop band are derived and verified in the numerical simulation section. The transmission peaks of single-cavity and two-cavity FP structures are compared and discussed, and results show that compared to the single-cavity FP, flatness of the top and steepness at the edge of transmission peak can be improved by introducing one more cavity. The resonant transmission peak properties of two-cavity structure are investigated in detail for various values of cavity length and FBGs with different reflection characteristics, and the design guidelines for transmission-type filters are presented. The results show that the steepness of peak slope can be improved by increase of FBG reflectivities, and these kinds of filters can be used as nar- row-band single-channel selectors and multi-channel wavelength de-multiplexing by properly choosing the length of cavities and reflectivities of FBGs.

关键词： fiber bragg gratings Fabry-Perot cavity transmission-type filter

Engineering approach to in-situ bridge health monitoring with fiber bragg gratings

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Journal of Harbin Institute of Technology(New Series) 2006年第5期13卷 588-594页

作者：武湛君张博明万里冰周智欧进萍 Conter for Composite Materials and Structures Harbin Institute of Technology Harbin 150001 China School of Civil Engineering Harbin Institute of Technology Harbin 150001 China

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.

关键词： fiber bragg gratings fiber optic sensors bridge strain structural health monitoring

Novel Technique for All-Optical Clock Extraction Using fiber bragg gratings

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光学学报 2003年第S1期23卷 597-598页

作者： M. Attygalle B. Ashton A. Nirmalathas L. Poladian W. Padden Australian Photonics Cooperative Research Centre Photonics Research Laboratory Department of Electrical and Electronic Engineering The University of Melbourne VIC 3010 Australia. Optical Fibre Technology Centre APCRC University of Sydney NSW 1430 Australia

We demonstrate a simple passive technique, using phase shifted fibre bragg gratings, for extraction of optical clock signals from RZ optical data signals. The generation of an optical clock signal at 12.5 GHz from a 12.5 Gbs RZ optical data stream is experimentally demonstrated with simulation of optical clock extraction at 10 GHz from 40 Gbs OTDM data streams.

关键词： fiber bragg gratings clock extraction data streams

fiber bragg gratings in Small-Core Ge-Doped Photonic Crystal fibers

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Journal of Electronic Science and Technology of China 2008年第4期6卷 429-433页

作者： Yiping Wang Hartmut Bartelt Wolfgang Ecke Reinhardt Willsch Jens Kobelke Michael Kautz Sven Brueckner Mantled Rothhardt Institute of Photonic Technology Albert-Einstein-Str.9 07745 Jcna Germany and State Key Lab of Advanced OpticalCommunication Systems and Networks Shanghai Jiaotong UniversityShanghai 200240 China Institute of Photonic Technology Albert-Einstein-Str. 9 07745 Jena Germany.

This paper reports fiber bragg gratings （FBGs） inscribed in a small-core Ge-doped photonic crystal fibers with a UV laser and a Talbot interferometer. The responses of such FBGs to temper- ature, strain, bending, and transverse-loading were systematically investigated. The bragg wavelength of the FBGs shifts toward longer wavelengths with increasing temperature, tensile strain, and transverse-loading. The bending and transverse- loading properties of the FBGs are sensitive to the fiber orientations.

关键词： fiber bragg gratings photonic crystal fibers optical fiber sensors.

Center of Gravity Estimation Using a Reaction Board Instrumented With fiber bragg gratings

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Photonic Sensors 2018年第1期8卷 1-6页

作者： Rui OLIVEIRA Paulo RORIZ Manuel B. MARQUES Orlando FRAZAO INESC TEC Rua do Campo Alegre 687 4150-179 Porto Portugal CIDESD-ISMAI-Institute University of Maia (ISMAl) Av. Carlos Oliveira Campos Castelo da Maia 4475-690 MaiaPortugal Department of Physics and Astronomy Faculty of Sciences University of Porto Rua do Campo Alegre 687 4169-007Porto Portugal

The purpose of the present work is to construct a reaction board based on fiber bragg gratings （FBGs） that could be used for estimation of the 2D coordinates of the projection of center of gravity （CG） of an object. The apparatus is consisted of a rigid equilateral triangular board mounted on three supports at the vertices, two of which have cantilevers instrumented with FBGs. When an object of known weight is placed on the board, the bending strain of the cantilevers is measured by a proportional wavelength shift of the FBGs. Applying the equilibrium conditions of a rigid body and proper calibration procedures, the wavelength shift is used to estimate the vertical reaction forces and moments of force at the supports and the coordinates of the object＇s CG projection on the board. This method can be used on a regular basis to estimate the CG of the human body or objects with complex geometry and density distribution. An example is provided for the estimation of the CG projection coordinates of two orthopaedic femur bone models, one intact, and the other with a hip stem implant encased. The clinical implications of changing the normal CG location by means of a prosthesis have been discussed.

关键词： Optical fiber sensors fiber bragg gratings cantilever center of gravity hip prosthesis