Multiplexed fiber-ring laser sensors for ultrasonic detection

Liu, Tongqing; Hu, Lei; Han, Ming

doi:10.1364/oe.21.030474

Cited by 23 publications

(7 citation statements)

References 15 publications

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“…Recently, extensive literature reports on OFAS have emerged. They can be roughly summarized into the following three categories [6]: Fiber grating type (including Bragg fiber grating FBG [7], long period fiber grating LPG [8], etc. ), Mach-Zehnder interferometer (MZI) [9] (including Sagnac [10], Michelson interferometer MI [11]), Fabry-Perot interferometer FPI [12].…”

Section: Introductionmentioning

confidence: 99%

Twice-FFT demodulation for signal distortion in optical fiber FP acoustic sensor

Xing

Jin

et al. 2020

Heliyon

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A Twice-FFT demodulation method for signal distortion state is proposed and experimentally demonstrated in an optical fiber Fabry-Perot (FP) acoustic sensor. Here the fiber FP acoustic sensor element is build with fiber end face and combination of diaphragms which is composed of a small round aluminum foil and a polymer PET film. The hypotenuse intensity demodulation method is applied to acquire the acoustic signal in time domain assisted with a Photodetector (PD) and an oscilloscope. The first Fast Fourier transform (FFT) processing results show harmonic distortion on the frequency domain spectrum. To demodulate the acoustic frequency and amplitude information, twice-FFT processing is preformed. Experimental results reveal an accuracy up to 95.6% of acoustic signal in the frequency range 2–100 Hz. Our scheme provides a new option for signal demodulation of optical fiber acoustic sensors (OFAS).

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Section: Introductionmentioning

confidence: 99%

Twice-FFT demodulation for signal distortion in optical fiber FP acoustic sensor

Xing

Jin

et al. 2020

Heliyon

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“…Then, two additional studies were conducted. One is the multiplexing ability achieved by cascading multiple ring cavities and the Fabry–Perot filters, though the complexity and cost of the system increased [ 64 ]. The other is the resistance to environmental disturbances by using a tandem FBG to replace the Fabry–Perot filter and gluing it at the same position as that of the FBG sensor.…”

Section: Demodulation Techniquesmentioning

confidence: 99%

Ultrasonic Structural Health Monitoring Using Fiber Bragg Grating

Okabe

2018

Sensors

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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.

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“…Previous approaches to improve the signal-to-noise ratio can be grouped into two categories; the first is to maximize the sensitivity of the FBG to strain in the optical fiber [3][4][5][6][7] and the second is to maximize the strain coupled to the optical fiber from Lamb waves in the structure by changing the bonding conditions [8,9]. Both approaches can also be applied simultaneously.…”

Section: Introductionmentioning

confidence: 99%

“…Examples of the first category include producing narrow bandwidth [3] or π-phase-shifted FBG designs to produce high spectral slopes for edge filtering [4,5]. Another example is the use of ring laser resonance configurations to amplify the measured signal in the optical fiber [6]. Tuning the length of the FBG to maximize the Lamb wavelength-to-FBG length ratio can also increase the sensitivity of detection [7].…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic Lamb wave measurement sensitivity of aligned carbon nanotube coated fiber Bragg grating

et al. 2019

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Fiber Bragg grating (FBG) sensors are typically bonded on the surface of a structure using an adhesive to collect ultrasonic waves for damage detection in structural health monitoring applications. However, the ultrasonic wave transfer from structure to optical fiber suffers signal attenuation due to the adhesive bond layer, which has a significantly different acoustic impedance than the optical fiber. Therefore, this paper develops a systematic procedure to fabricate an aligned carbon nanotube (CNT)-wrapped FBGs for acoustic impedance matching. Specifically, we first develop an automated CNT winding system to fabricate CNT-wrapped FBGs with varying CNT layer thickness, which are bonded to an aluminum plate for ultrasonic sensitivity testing. We demonstrate that CNT wrapped FBGs do not necessarily produce an increased sensitivity as compared to a reference polyimide-coated FBG, however some outliers are observed with a significant improvement. Using a scanning electron microscopy we examine the cross-section of CNT/adhesive layers, identifying a unique CNT/ adhesive bonding morphology with a stiff exterior shell and a relatively compliant inner layer. Finite element simulation validates that this two-layered bonding geometry is most likely the source of the increased FBG ultrasonic sensitivity for the outliers.

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Multiplexed fiber-ring laser sensors for ultrasonic detection

Cited by 23 publications

References 15 publications

Twice-FFT demodulation for signal distortion in optical fiber FP acoustic sensor

Twice-FFT demodulation for signal distortion in optical fiber FP acoustic sensor

Ultrasonic Structural Health Monitoring Using Fiber Bragg Grating

Ultrasonic Lamb wave measurement sensitivity of aligned carbon nanotube coated fiber Bragg grating

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