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Fiber Bragg Grating (fiber + bragg_grating)

Distribution by Scientific Domains

Engineering	87%

Selected Abstracts

Quaternary phase coding and decoding of short pulses at 40 Gb/s using superstructured fiber BRAGG gratings

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2006
Xiaogang Chen
Abstract A three-chip, 240-Gchip/s quaternary phase-shift code is assigned to short pulses after reflection from a encoder. The code is then recognized by a decoder. The encoder and decoder consist of superstructured fiber Bragg gratings (SSFBGs). The quaternary phase encoding and decoding of short pulses at 40 Gb/s is experimentally demonstrated, and it is required in optical-code division multiplexing (OCDM) systems and packet-switched networks. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 575,577 2006; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21411 [source]

Health Monitoring of Rehabilitated Concrete Bridges Using Distributed Optical Fiber Sensing

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2006
Wei Zhang
As newly developed techniques, distributed optical fiber sensing (DOFS) have gradually played a prominent role in structural health monitoring for the last decade. This article focuses on the employment of two types of DOFS, namely fiber Bragg grating (FBG) and Brillouin optical time domain reflectometry (BOTDR), into an integrated HMS for rehabilitated RC girder bridges by means of a series of static and dynamic loading tests to a simply supported RC T-beam strengthened by externally post-tensioned aramid fiber reinforced polymer (AFRP) tendons. Before the loading tests, a calibration test for FBG and another one for BOTDR were implemented to, respectively, obtain good linearity for both of them. Monitoring data were collected in real time during the process of external strengthening, static loading, and dynamic loading, respectively, all of which well identified the relevant structural state. The beam was finally vibrated for 2 million cycles and then loaded monotonously to failure. Based on the bending strength of externally prestressed members, ultimate values for the test specimen were numerically computed via a newly developed simplified model, which satisfactorily predicted the ultimate structural state of the beam. And then the alert values were adopted to compare with the monitoring results for safety alarm. The investigation results show a great deal of applicability for the integrated SHM by using both DOFS in rehabilitated concrete bridges strengthened by external prestressing. [source]

Multi-wavelength fiber laser in the S-band region using a Sagnac loop mirror as a comb generator in an SOA gain medium

LASER PHYSICS LETTERS, Issue 9 2010
M.Z. Zulkifii
Abstract A simple design of multi-wavelength generation in the S-band region of the optical network transmission is proposed. The design consists of broad-band fiber Bragg grating (BB-FBG), which acts as a filter to enhance operation in the S-band region. A Sagnac loop mirror (SLM) is used to generate multiple wavelength oscillations in the ring cavity. The output consists of 60 lasing wavelengths oscillating simultaneously between 1464 nm and 1521 nm with a spacing of 0.92 nm and an output linewidth of 0.66 nm. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

An overview on S-band erbium-doped fiber amplifiers

LASER PHYSICS LETTERS, Issue 1 2007
S. W. Harun
Abstract An erbium-doped fiber amplifier (EDFA) for S-band signal amplification is designed by using a depressed cladding erbium-doped fiber (DC-EDF). The fiber's characteristics are described in terms of the effects of the fiber spooling diameter on the amplifier's performance. In this experiment, the spooling diameter required for optimum amplifier gain was around 5,7 cm. By using a typical two-stage configuration (with a 27 m long DC-EDF and a 260 mW pump laser power), the maximum small signal gain obtained was about 32 dB. Yet, by employing a double pass amplifier configuration with a shorter DC-EDF length and a lower pump laser power (15 m and 135 mW, respectively), a similar maximum small signal gain of approximately 30 dB was achieved. This improvement in gain characteristics however, incurred an increased noise figure penalty of about 1 dB in comparison to single-pass amplifier configurations. In order to reduce the amplifier's noise figure while maintaining its high gain, a partial double-pass S-band EDFA configuration was introduced. This configuration provides a high 26.9 dB gain and an improved noise figure comparable to a single pass configuration. Gain clamping in S-band EDFAs are also demonstrated by utilizing a fiber Bragg grating to form an oscillating laser at around 1530 nm. This technique enables good gain clamping with a gain variation of less than 1 dB. (© 2007 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Implementation of tunable erbium doped fiber laser using a broadband fiber mirror

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2008
Shien-Kuei Liaw
Abstract By using a broadband fiber mirror (BFM), a wavelength tunable erbium-doped fiber laser (TEDFL) is demonstrated composed with tunable fiber Bragg grating (TFBG). The BFM acts as a broadband reflector both for the lasing signal and pump source. At pumping power of 100 mW, stable laser output power of 21.35 dBm is obtained at a low threshold pumping power of 4.7 mW. A side mode suppression ratio (SMSR) of 57.9 dB and 16 nm wavelength scan range are demonstrated using a single TFBG. The tunable fiber laser may be a good candidate for vast applications in optical network technologies. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1722,1724, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23510 [source]

A simple method for simultaneous measurement of the tilt angle and temperature

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2007
Jinhua Yan
Abstract A simple and compact sensor for simultaneous measurement of the tilt angle and temperature is presented. The sensor is composed of a fiber taper and a fiber Bragg grating. The tilt angle is measured by monitoring the tilt-induced loss of the taper. The grating is used for enhancing the tilt angle sensitivity as well as monitoring the wavelength shift induced by the temperature variation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2248,2250, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22701 [source]

Optical mm-wave generation based on phase modulation along with optical filtering

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2007
Jianxin Ma
Abstract We have investigated the generation and transmission of optical millimeter (mm)-wave signal based on optical phase modulator (PM) and fiber Bragg grating (FBG) filter. With an optimized modulation depth of PM and a higher carrier suppression ratio via a notch filter, the generated optical mm-wave can be transmitted over a long-distance without fading. We have also theoretically analyzed the impact of time shift on the eye closure of optical and electrical signal due to the fiber dispersion, which is well in accord with the experimental results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1787,1793, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22622 [source]

Analyzing longitudinal-mode of single-frequency ring fiber laser

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2007
T. S. Wang
Abstract To realize single-frequency of the fiber laser, a ring configuration is devised. The single-frequency operation is realized at 1549.63 nm by using a fiber Bragg grating (FBG) as wavelength-selective element and a unpumped 1.5 m-long erbium-doped fiber, which can produce standing-wave saturation effects in the cavity. A measurement method based on fiber-coupling scanning Fabry,Perot (F-P) interferometer at 1.55 ,m is designed. The laser longitudinal-mode spacing is 11.1 MHz. The single-frequency is observed by the interferometer with free spectrum range (FSR) of 7.5 GHz. The longitudinal-mode fabric is analyzed by the interferometer with FSR of 1.5 GHz. As the cavity length increases, the longitudinal-mode spacing changes to 3.7 MHz. The structures of longitudinal-modes under different cavity lengths are compared. The longitudinal-mode linewidth of 20 MHz is measured. Experimental results show that single-frequency of the fiber laser can be approved accurately, and the effectiveness of the method, which can analyze longitudinal-mode of the fiber laser with scanning Fabry,Perot (F-P) interferometer, is improved. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1494,1497, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22467 [source]

High-power narrow line width tunable cladding pumped Er:Yb co-doped fiber laser

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2006
Shu-min Zhang
Abstract A narrow line width, tunable, and highly efficient fiber laser based on Er3+/Yb3+ co-doped double-clad fiber with the maximum output power of 438 mW and a slope efficiency of ,16% has been demonstrated. By using a fiber Bragg grating (FBG) as a narrow band reflector, 3-dB line width of the output laser could be as narrow as 0.04 nm over the whole tuning range, and by compressing or stretching the FBG, wavelength tunable range of 4.0 nm was realized. In the experiment, we also found that there existed an optimum splitting ratio of the output coupler, at which the maximum output power could reach ,647 mW. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1736,1739, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21762 [source]

Experimental investigation on chemical sensor based on a multimode fiber Bragg grating

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2006
Xinzhu Sang
Abstract A chemical sensor based on a Bragg grating in the multimode fiber has been demonstrated experimentally. Experimental results indicate that the reflection peak of high-order mode P2 exhibits a much higher concentration sensitivity of the chemical solution than the reflection peak P1 of the high-order mode. The sensor has been used to measure the concentrations of propylene glycol solutions and sugar solutions, which could detect 0.05% and 0.04% concentration change for them with the wavelength interrogation module of 1-pm resolution. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1739,1741, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21761 [source]

Impact of the pump reflector in double-pass discrete Raman amplifiers

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2006
M. I. Md Ali
Abstract We present the experimental investigation of a counter-pumped double-pass discrete Raman amplifier with and without a pump reflector. The pump reflector is constructed with high-reflectivity fiber Bragg grating. Gain improvement is obtained as a result of pump recycling, in comparison to the conventional double-pass Raman amplifier. Noise-figure degradation is found for large signals in the proposed Raman amplifier due to the enhanced double-Rayleigh scattering and bidirectional pumping caused by the pump reflector. The impact of pump-to-signal relative intensity noise in the experimental work is minimized by utilizing Fabry,Perot pump lasers. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 777,779, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21473 [source]

Bend sensor using an embedded etched fiber Bragg grating

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2004
Yong-Sen Yu
Abstract We present a new bend sensor which can measure the curvature using an etched fiber Bragg grating (FBG) embedded into a beam. The reflection power of the grating detected by an optical power meter varies linearly with the curvature of the beam. This sensor is independent of temperature. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 414,417, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20486 [source]

Actively Q-switched all-fiber lasers

LASER PHYSICS LETTERS, Issue 2 2008
M.V. Andrés
Abstract Q-switching of fiber lasers using bulk elements has important drawbacks as reduced mechanical stability and high insertion losses. The development of efficient all-fiber modulation techniques is the key to obtain robust, compact and efficient Q-switched all-fiber lasers. Certainly, the development of fiber Bragg gratings (FBG) has been crucial to make progress on fiber lasers. FBGs permit a simple way to assemble all-fiber laser cavities and can be written in the active fiber itself. The Q-factor of this type of cavities is determined by the reflectivity of the FBGs and the losses of the fiber. Here, we focus on the use of magnetostrictive materials and the acousto-optic interaction to develop efficient Q-factor modulators. Most of these modulators include an FBG and take advantage of the specific interaction of the magnetostrictive materials or the acoustic wave with the FBG itself. Fiber optic technologies permit the development of a rather unique type of fiber lasers, i.e., actively Q-switched distributed feedback (DFB) fiber lasers. In this case, both the use of magnetostrictive materials and the acousto-optic interaction permit the generation of dynamic defects in an FBG that has been previously written in a highly Er-doped fiber. (© 2007 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Novel design of multiplexed sensors using a dual FBGs scheme

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2010
S. Nafisah
Abstract We propose a new system of the multiplexed sensors using a series of fiber Bragg gratings (FBGs), where the gratings separation lengths, Bragg wavelength, dip length, and birefringence can be configured as the sensing information. The transmission spectrum of a dual fiber Bragg gratings has been derived. Value of separation length between two FBGs, dL, is varied from 0.5 to 5.5 cm. The dip of separation length affects the transmission spectrum, which is indicated by the numbers of minimum dip values. Results show that the increasing in the separation length (dip length) between two FBGs leads to the formation of phase shift and increases the number of minimum transmission dip. For the dual FBGs to be used as a Fabry-Perot interferometer, it must have the smallest possible separation length. The multiplexed sensing application of more than two physical parameters can be operated by using such effects, for instance, strain, temperature, and gas sensor is plausible, while the self calibration between them is also available. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1218,1221, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25106 [source]

Optical fiber sensor for localizing heating positions in multiple points using multichannel gratings with phase sampling and wavelength division multiplexing techniques

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2008
Li Xia
Abstract An optical fiber sensor system with multichannel fiber Bragg gratings (FBGs) is proposed. The gratings are designed and fabricated by phase sampling technique within strongly chirped phase masks. The sensing application can be realized at multiple points through wavelength division multiplexing (WDM) technique. It means that the different point can be monitored by different gratings, which occupies different wavelength region, according to the central pitch and chirp coefficient of phase masks. The heating position with high resolution can be analyzed through three corresponding channel shifts in the multichannel profile. In our experiment, the two multichannel gratings with channel spacing of 0.8 and 1.6 nm, respectively, are fabricated and used for sensing in two points. At last, the 400 ,m accuracy of localizing the heating position is achieved. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2951,2954, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23832 [source]

Apodization of fiber Bragg gratings by using ARC discharges

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2008
R. Romero
Abstract The electric arc technique is used to apodize fiber Bragg gratings (FBGs). Arc discharges applied to the ends of the grating produce a smoothing of the refractive-index modulation profile reducing the sidelobes of the reflection spectrum at longer wavelengths. A sidelobe reduction of 17 dB was obtained. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 316,319, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23056 [source]

Reconfigurable multiwavelength erbium-doped fiber laser using two multimode fiber Bragg gratings

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2007
Jin-Hua Yan
Abstract A reconfigurable multiwavelength erbium-doped fiber laser, using two multimode fiber Bragg gratings (MFBGs), is presented. Two MFBGs in L-band are cascaded to form two overlapping resonant cavities. Various configurations of four-, three-, or two-wavelength lasing are demonstrated experimentally by appropriately controlling the two polarization controllers inside the cavities. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1509,1511, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22493 [source]

Tunable flat-top fiber Bragg grating filters fabricated in hydrogen-loaded graded-index multimode fibers

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2007
Hong-Yan Fu
Abstract We propose an experimental realization of flat-top filters by fabricating fiber Bragg gratings in graded-index multimode fibers (GI-MMF). Two types of GI-MMFs were used to make this kind of filters, and their spectra and polarization properties were experimentally investigated. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 841,843, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22286 [source]

A tunable photonic RF notch filter based on opto-VLSI technology

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2006
Rong Zheng
Abstract In this paper, we propose a novel tunable transversal photonic RF notch filter based on opto-VLSI technology. By using an array of fiber Bragg gratings (FBGs) in conjunction with an opto-VLSI processor, the broadband light source can be spectrally sliced and attenuated, hence realizing a two-tap RF notch filter with stepwise true-time delays and variable weights. In addition, the free spectral frequency and notch depth of the RF notch filter can be tuned by driving the opto-VLSI processor with optimized phase-only holograms. We experimentally demonstrate the proposed tunable RF notch filter structure and the results show that a notch depth greater than 40 dB can be attained. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1011,1015, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21586 [source]