1,721,065 research outputs found
Evaluation of a high spatial resolution temperature compensated distributed strain sensor using a temperature controlled strain rig
No full textWe demonstrate a scheme which allows for temperature corrected distributed strain measurements under environments involving simultaneous application of strain and temperature, with enhanced spatial (5 cms), strain (66 µ.epsilon) and temperature resolutions (1.9°C). The technique utilizes the combination of frequency based BOCDA with Brillouin intensity measurements
A method of increasing the range of 1.65µm long range OTDR system based on Raman amplification
Full text linkOptical Time Domain Reflectometry (OTDR) is an efficient and reliable technique for locating fibre faults and determining the loss distribution along the fibre. An OTDR system operating at a wavelength of 1.65µm is more sensitive to fibre macro-bending and micro-bending losses than those at the region of 1.3/1.55µm, thus providing an early detection of system faults and reducing the risk of total system failure. The current limitation in the maximum dynamic range of OTDR systems is due to the low power of 1.65µm laser diodes. Raman amplification has been employed to amplify a 1.66µm laser diode pulse by 24.8dB before launching it down the end of a sensing fibre. We propose a novel method of increasing the dynamic range of a 1.65µm OTDR system through the use of delayed Raman amplification within the sensing fibre. By delaying the pump pulse with respect to the OTDR pulse, amplification of the latter may be delayed by tens of kilometres
Detection bandwidth of fibre-optic current sensors based on Faraday effect
No full textCurrent sensing based on the Faraday Effect in optical fibers is a well-established area in the landscape of sensor technologies. However, the optical behavior that sets an upper limit on the detection bandwidth is often overlooked. The underlying mechanisms are explored in this analysis to raise awareness about their impact on the measurement results. These findings show that the Faraday Effect cancellation and pulse broadening grow with increasing signal frequency, which result in suppression and distortion of the optical response. A correction factor is proposed for alternating and pulsed signals when using the simplified equation, to maintain an accurate measure of the peak current
Brillouin-based distributed fibre temperature sensor at 1.53µm using Raman amplification
No full textThis paper describes the first demonstration of increasing the dynamic range of Brillouin-based distributed temperature sensor at 1533 nm using Raman amplification provided by a 1450 nm pump source
Diode pumped high power simultaneously Q-switched and self mode-locked erbium doped fibre laser
No full textWe report for the first time a diode pumped electro-optically Q-switched and mode-locked Erbium doped fibre laser. Simultaneous Q-switching and mode-locking produces 4 ns pulses of 540 Watts peak power in a 20 ns Q-switched envelope
Sub-metre spatial resolution temperature compensated distributed strain sensor
No full textWe propose and demonstrate a scheme which utilizes the temperature dependence of spontaneous Raman scattering to provide temperature compensation for a sub-metre spatial resolution Brillouin frequency based strain sensor. Temperature compensated strain sensor measurements have been demonstrated with a strain resolution of 94µ.ε and a spatial resolution of 10cms. This paper describes the combination of Brillouin frequency based BOCDA technique [1] with an independent measurement of temperature, based on the determination of the intensity of the anti-Stokes Raman scattering (R-OTDR) with very much higher spatial resolution than previously reported [2], in order to produce a fully temperature compensated strain sensor with high spatial resolution
Temperature compensated sub-metre spatial resolution distributed strain sensor
No full textTemperature compensated strain sensor measurements are demonstrated with strain resolution of 86 µ.epsilon and spatial resolution of 26cms, utilising temperature dependence of spontaneous Raman scattering for temperature compensated sub-metre spatial resolution Brillouin frequency based strain sensor
Landau Placzek ratio applied to distributed fibre sensing
No full textIt is shown experimentally that the ratio of the intensities of Rayleigh and Brillouin backscattered light (Landau Placzek ratio) in an optical fibre has a temperature dependence which may be used for the basis of a distributed temperature sensor. This result, combined with the known frequency dependence of be Brillouin backscattering on temperature and strain, indicates that spontaneous Brillouin backscatter may be used for the unique determination of either temperature or strain in a distributed optical fibre sensing system
Data set for the numerical analysis of distributed optical fibre acoustic sensing
No full textThis data set provides the data of the diagrams in the manuscript submitted to Journal of Lightwave technology. Masoudi, A., & Newson, T. P. (2017). Analysis of distributed optical fibre acoustic sensors through numerical modelling. Optics Express, 25(25), 32021-32040. DOI: 10.1364/OE.25.032021</span
1.5µm Brillouin-based fibre optic distributed temperature sensor with high spatial resolution of 20cm
No full textWe demonstrate a high spatial resolution single-ended spontaneous Brillouin-based distributed temperature sensor for a 500m length of single-mode silica fibre. Using a short pulsewidth laser source at 1.5µm, measurements down to a spatial resolution of 20cm and temperature resolution of 4.4°C were achieved
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