Fiber-Optic Vibration Sensor Based on Beat Frequency and Frequency-Modulation Demodulation Techniques

Gao, Liang; Liu, Shengchun; Yin, Zuowei; Zhang, Liang; Chen, Lin; Chen, Xiangfei

doi:10.1109/lpt.2010.2089612

Cited by 42 publications

(11 citation statements)

References 9 publications

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“…Recently, fiber-optic vibration (or, equivalently, acceleration) sensors have received more attention than their electrical counterparts because of their inherent superiority, as described above [84,85,86,87,88,89,90,91,92,93,94,95,96]. In particular, FBG accelerometers have undergone rapid development and have established themselves as the leading technology, compared to other fiber sensor technologies.…”

Section: Functional Fbg Sensorsmentioning

confidence: 99%

Fiber Bragg Grating Sensors for the Oil Industry

Qiao

Shao

Bao

et al. 2017

Sensors

173

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With the oil and gas industry growing rapidly, increasing the yield and profit require advances in technology for cost-effective production in key areas of reservoir exploration and in oil-well production-management. In this paper we review our group’s research into fiber Bragg gratings (FBGs) and their applications in the oil industry, especially in the well-logging field. FBG sensors used for seismic exploration in the oil and gas industry need to be capable of measuring multiple physical parameters such as temperature, pressure, and acoustic waves in a hostile environment. This application requires that the FBG sensors display high sensitivity over the broad vibration frequency range of 5 Hz to 2.5 kHz, which contains the important geological information. We report the incorporation of mechanical transducers in the FBG sensors to enable enhance the sensors’ amplitude and frequency response. Whenever the FBG sensors are working within a well, they must withstand high temperatures and high pressures, up to 175 °C and 40 Mpa or more. We use femtosecond laser side-illumination to ensure that the FBGs themselves have the high temperature resistance up to 1100 °C. Using FBG sensors combined with suitable metal transducers, we have experimentally realized high- temperature and pressure measurements up to 400 °C and 100 Mpa. We introduce a novel technology of ultrasonic imaging of seismic physical models using FBG sensors, which is superior to conventional seismic exploration methods. Compared with piezoelectric transducers, FBG ultrasonic sensors demonstrate superior sensitivity, more compact structure, improved spatial resolution, high stability and immunity to electromagnetic interference (EMI). In the last section, we present a case study of a well-logging field to demonstrate the utility of FBG sensors in the oil and gas industry.

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Section: Functional Fbg Sensorsmentioning

confidence: 99%

Fiber Bragg Grating Sensors for the Oil Industry

Qiao

Shao

Bao

et al. 2017

Sensors

173

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“…In 2010, Shengchun Liu reported a multi‐longitudinal mode fiber sensor formed by two fiber Bragg gratings and a piece of erbium doped fiber for strain measurement . Besides, many other optical sensors have been reported based on beat frequency demodulation . Recently, a new method based on incoherent heterodyne interferometry has been proposed by measuring the free spectral range (FSR) of the ring interferometers containing a FUT and this method has successfully been applied to the GD measurement of the single‐mode fiber (SMF) and dispersion‐shifted fiber (DSF) .…”

Section: Introductionmentioning

confidence: 99%

Optical fiber group delay measurement based on laser beat frequency

Wang

Wen

et al. 2017

Micro & Optical Tech Letters

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A new method for optical fiber group delay measurement is proposed and experimentally demonstrated based on laser beat frequency. When the laser wavelength in the optical fiber resonator changes, the time delay through the optical fiber under test will change accordingly, leading to a change of round trip time in the optical fiber laser resonator. While the round trip time is the reciprocal of the minimum beat frequency, the group delay of the optical fiber under test which is placed in the fiber laser resonator can be easily obtained by measuring the beat frequency variation via the radio frequency spectrum analyzer. The optical fiber laser resonator utilized in experiments is composed of two reflectors: one is a sagnac loop composed of a coupler, the other is a composite structure composed of an optical circulator connected with a Fiber Fabry‐Perot Tunable Filter. The group delay of the single‐mode fiber and the dispersion compensating fiber are measured respectively in a relatively wide spectral range. Experimental results show that this method is feasible. Furthermore, this method is of very simple structure and low cost compared with other conventional methods.

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“…The proposed demodulation system becomes simpler and cheaper. It has been used successfully to measure the strain, temperature and vibration [14][15][16]. The strain and temperature of the MLMFL sensor are simultaneously monitored by multi-longitudinal mode beat frequency and polarization mode beat frequency [17].…”

Section: Introductionmentioning

confidence: 99%