Analysis of $\pi$ -Phase-Shifted Fiber Bragg Gratings for Ultrasonic Detection
06 Mar 2012-IEEE Sensors Journal (Institute of Electrical and Electronics Engineers Inc.)-Vol. 12, Iss: 7, pp 2368-2373
TL;DR: In this paper, the responses of π-phase-shifted fiber Bragg gratings (πFBGs) impinged by pressure ultrasonic waves were investigated using numerical simulations, and the effect of the grating length, grating refractive index modification depth, and ultrasonic frequency on the wavelength sensitivity and intensity sensitivity of the πFBG ultrasonic sensor was analyzed.
Abstract: Using numerical simulations, we investigated the responses of the π -phase-shifted fiber Bragg gratings (πFBGs) impinged by pressure ultrasonic waves. The effect of the grating length, grating refractive index modification depth, and ultrasonic frequency on the wavelength sensitivity and intensity sensitivity of the πFBG ultrasonic sensor for ultrasonic waves of different wavelengths was analyzed. The directivity of a πFBG sensor was also studied. Our analysis revealed several unique πFBG response characteristics and will be useful in the design and optimization of fiber-optic ultrasonic sensors that use a πFBG as the sensing element.
Citations
More filters
TL;DR: Fiber Bragg grating has embraced the area of fiber optics since the early days of its discovery, and most fiber optic sensor systems today make use of fiber Bragg-grating technology as discussed by the authors.
Abstract: Fiber Bragg grating has embraced the area of fiber optics since the early days of its discovery, and most fiber optic sensor systems today make use of fiber Bragg grating technology Researchers have gained enormous attention in the field of fiber Bragg grating (FBG)-based sensing due to its inherent advantages, such as small size, fast response, distributed sensing, and immunity to the electromagnetic field Fiber Bragg grating technology is popularly used in measurements of various physical parameters, such as pressure, temperature, and strain for civil engineering, industrial engineering, military, maritime, and aerospace applications Nowadays, strong emphasis is given to structure health monitoring of various engineering and civil structures, which can be easily achieved with FBG-based sensors Depending on the type of grating, FBG can be uniform, long, chirped, tilted or phase shifted having periodic perturbation of refractive index inside core of the optical fiber Basic fundamentals of FBG and recent progress of fiber Bragg grating-based sensors used in various applications for temperature, pressure, liquid level, strain, and refractive index sensing have been reviewed A major problem of temperature cross sensitivity that occurs in FBG-based sensing requires temperature compensation technique that has also been discussed in this paper
163 citations
TL;DR: A novel technology of ultrasonic imaging of seismic physical models using FBG sensors, which is superior to conventional seismic exploration methods and demonstrates superior sensitivity, more compact structure, improved spatial resolution, high stability and immunity to electromagnetic interference (EMI).
Abstract: 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.
147 citations
TL;DR: A novel highly sensitive ultrasound sensor based on a random fiber laser that offers signal-to-noise ratio improvement up to 20 dB and higher sensitivity compared with conventional piezoelectric acoustic sensors is proposed and demonstrated.
Abstract: A novel highly sensitive ultrasound sensor based on a random fiber laser is proposed and demonstrated for the first time, to the best of our knowledge. The random fiber laser is constructed with the erbium-doped fiber gain. A fiber random grating provides random-distributed feedback for the random laser and acts as an ultrasound sensing head. The random laser can operate in a single-mode lasing scenario, which offers linear and pure temporal responses to the broadband ultrasonic acoustic emission from 20 kHz to 0.8 MHz. The multiple-interfering reflection spectrum of the random grating provides a large number of steep peak areas over a broad spectral range, which significantly enhances the sensitivity of the random laser sensor and makes it an ideal sensor in harsh environments with large temperature or strain variations. The proposed laser sensor offers signal-to-noise ratio improvement up to 20 dB and higher sensitivity compared with conventional piezoelectric acoustic sensors.
77 citations
TL;DR: In this paper, a phase-shifted fiber Bragg grating (PS-FBG) sensing system based on Pound-Drever-Hall (PDH) technique is proposed and experimentally demonstrated for ultrasonic detection.
Abstract: A phase-shifted fiber Bragg grating (PS-FBG) sensing system based on Pound–Drever–Hall (PDH) technique is proposed and experimentally demonstrated for ultrasonic detection. The sensing system is highly stabilized as the laser is frequency locked to the PS-FBG resonance using PDH technique. This scheme reduces the effect of laser intensity noise and enables high-sensitivity ultrasonic detection by monitoring the error signal of frequency detuning between the laser and the PS-FBG resonance. Response of the frequency-locked PS-FBG to ultrasound is done by testing the ultrasonic refection of a 0.4-mm plastic film, immersed in water. The sensor exhibits a high signal-to-noise ratio of 48 dB at 200 kHz and a noise-limited detectable strain of 8.7 $\text{p}\varepsilon $ above 10 kHz. Frequency response of PS-FBG from 100 kHz to 1 MHz was also characterized.
67 citations
Cites background from "Analysis of $\pi$ -Phase-Shifted Fi..."
...2396530 to achieve broader bandwidth and higher sensitivity [12]....
[...]
TL;DR: In this review, the mature techniques of FBG-based ultrasonic sensors and their practical applications in ultrasonic structural health monitoring are discussed and state-of-the-art techniques are introduced to fully present the current developments.
Abstract: The fiber Bragg grating (FBG) sensor, which was developed over recent decades, has been widely used to measure manifold static measurands in a variety of industrial sectors. Multiple experiments have demonstrated its ability in ultrasonic detection and its potential in ultrasonic structural health monitoring. Unlike static measurements, ultrasonic detection requires a higher sensitivity and broader bandwidth to ensure the fidelity of the ultrasonic Lamb wave that propagates in a plate-like structure for the subsequent waveform analysis. Thus, the FBG sensor head and its corresponding demodulation system need to be carefully designed, and other practical issues, such as the installation methods and data process methods, should also be properly addressed. In this review, the mature techniques of FBG-based ultrasonic sensors and their practical applications in ultrasonic structural health monitoring are discussed. In addition, state-of-the-art techniques are introduced to fully present the current developments.
66 citations
References
More filters
Book•
01 Jan 1985
TL;DR: In this paper, the physical properties of crystals systematically in tensor notation are presented, presenting tensor properties in terms of their common mathematical basis and the thermodynamic relations between them.
Abstract: First published in 1957, this classic study has been reissued in a paperback version that includes an additional chapter bringing the material up to date. The author formulates the physical properties of crystals systematically in tensor notation, presenting tensor properties in terms of their common mathematical basis and the thermodynamic relations between them. The mathematical groundwork is laid in a discussion of tensors of the first and second ranks. Tensors of higher ranks and matrix methods are then introduced as natural developments of the theory. A similar pattern is followed in discussing thermodynamic and optical aspects.
8,520 citations
"Analysis of $\pi$ -Phase-Shifted Fi..." refers background in this paper
...where E and υ are the Young’s modulus and the Poisson’s ratio; and P11 and P12 are the two independent elements of the strain-optic tensor for the πFBG material [9]....
[...]
TL;DR: In this paper, the spectral properties of fiber reflection and transmission gratings are described and examples are given to illustrate the wide variety of optical properties that are possible in fiber gratings.
Abstract: In this paper, we describe the spectral characteristics that can be achieved in fiber reflection (Bragg) and transmission gratings. Both principles for understanding and tools for designing fiber gratings are emphasized. Examples are given to illustrate the wide variety of optical properties that are possible in fiber gratings. The types of gratings considered include uniform, apodized, chirped, discrete phase-shifted, and superstructure gratings; short-period and long-period gratings; symmetric and tilted gratings; and cladding-mode and radiation-mode coupling gratings.
3,330 citations
"Analysis of $\pi$ -Phase-Shifted Fi..." refers background or methods in this paper
...The complex amplitudes of the optical modes before and after the i th uniform grating session are related by a 2 × 2 matrix Fi such as [10] [ Ri Si ] = Fi [ Ri−1 Si−1 ] = [ F11 F12 F21 F22 ] [ Ri−1 Si−1 ]...
[...]
...where Ri and Si are the complex amplitudes of the forward and backward traveling modes after the i th session, and the elements in Fi are defined by [10]...
[...]
TL;DR: The use of a fiber-optic Mach-Zehnder interferometer to measure differences in temperature or pressure between two single-mode fiber arms is described.
Abstract: The use of a fiber-optic Mach-Zehnder interferometer to measure differences in temperature or pressure between two single-mode fiber arms is described. Temperature or pressure changes are observed as a motion of an optical interference fringe pattern. Values are calculated for the pressure and temperature dependence of the fringe motion. Pressure and temperature measurements are made with the interferometer, and the experimental values for sensitivity are in good agreement with those calculated.
669 citations
"Analysis of $\pi$ -Phase-Shifted Fi..." refers background in this paper
...The relative changes to the refractive index and the grating period due to the pressure wave in the fiber can be written as [4, 8]...
[...]
TL;DR: A unified approach to obtain the characteristics of almost-periodic grating slab waveguides including gain in the waveguide is reported and it is shown that the F matrix can be used to obtaining the threshold conditions for distributed feedback laser oscillations including reflections from cleaved edges.
Abstract: A unified approach to obtain the characteristics of almost-periodic grating slab waveguides including gain in the waveguide is reported. In this approach the waveguides are divided into short segments, and in each segment the gratings are assumed to be periodic, that is, parameters such as coupling coefficient, grating phase, deviations from the Bragg frequency, and gain in the waveguide are independent of a propagation direction z. Then characteristics of almost-periodic grating slab waveguides can be obtained by multiplying each F matrix of a short segment with the proper grating phase conditions at the interface between two adjacent segments. The appropriateness of this approach is shown for typical aperiodic grating waveguides such as tapered, chirped, and phase-shifted gratings. The results obtained by this method are compared with others and prove to be in good agreement with the results obtained by other methods. In addition to these characteristics, it is shown that the F matrix can be used to obtain the threshold conditions for distributed feedback laser oscillations including reflections from cleaved edges.
630 citations
TL;DR: A highly sensitive compact hydrophone, based on a pi-phase-shifted fiber Bragg grating, has been developed for the measurement of wideband ultrasonic fields, which makes the design attractive for medical imaging applications, such as optoacoustic tomography, in which compact, sensitive, and wideband acoustic detectors are required.
Abstract: A highly sensitive compact hydrophone, based on a pi-phase-shifted fiber Bragg grating, has been developed for the measurement of wideband ultrasonic fields. The grating exhibits a sharp resonance, whose centroid wavelength is pressure sensitive. The resonance is monitored by a continuous-wave (CW) laser to measure ultrasound-induced pressure variations within the grating. In contrast to standard fiber sensors, the high finesse of the resonance--which is the reason for the sensor's high sensitivity--is not associated with a long propagation length. Light localization around the phase shift reduces the effective size of the sensor below that of the grating and is scaled inversely with the resonance spectral width. In our system, an effective sensor length of 270 μm, pressure sensitivity of 440 Pa, and effective bandwidth of 10 MHz were achieved. This performance makes our design attractive for medical imaging applications, such as optoacoustic tomography, in which compact, sensitive, and wideband acoustic detectors are required.
234 citations
"Analysis of $\pi$ -Phase-Shifted Fi..." refers background in this paper
...2189383 of attention for their highly sensitive ultrasonic detection [6, 7]....
[...]