Dynamic and random-access strain measurement by fiber Bragg gratings with synthesis of optical coherence function

Enyama, Momoyo; Hotate, Kazuo

doi:10.1117/12.571357

Cited by 12 publications

(11 citation statements)

References 4 publications

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“…5 However, in the case of high measurement speed, in other words, high speed sweeping of the center frequency, we noticed that the frequency sweeping has a bad effect on the SOCF and the delta-function-like coherence function shown in Fig. 1 cannot be observed.…”

Section: Performance Limiting Factor and Its Solutionsmentioning

confidence: 86%

“…2. 5 It consists of an interference system between the reference light and the reflection light from FBGs. The interference is observed by using the heterodyne detection.…”

Section: Principle Of Multiplexed Fbg Strain Sensor By Socfmentioning

confidence: 99%

“…[1][2][3][4] By using the technique of synthesis of optical coherence function (SOCF), we have developed a multiplexed FBG strain sensor system with FBGs of the same Bragg wavelength. 5 Up to date, the interrogation speed of the system is 100 Hz. It means that the interrogation speed for each FBG is 1 Hz if 100 FBGs are multiplexed in the array.…”

Section: Introductionmentioning

confidence: 99%

“…Basic setup for multiplexing FBGs with the same Bragg wavelength by the synthesis of optical coherence function 5. …”

mentioning

confidence: 99%

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High-speed interrogation of multiplexed fiber Bragg grating sensors with similar Bragg wavelength by synthesis of optical coherence function

Hayashi

Hotate

2005

Fiber Optic Sensor Technology and Applications IV

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We have reported recently a multiplexed fiber Bragg grating (FBG) strain sensor by using the technique of synthesis of optical coherence function. By modulating the optical frequency of the light source in a sinusoidal waveform, the coherence function is synthesized into a series of periodical peaks in the meaning of time-integration. Using one of the coherence peaks as a measurement window, and sweeping it along a string of FBGs by adjusting the repetitive frequency of the sinusoidal modulation waveform, we can selectively pick up the reflection as interference signal from any one FBG from the string. Therefore, the FBGs are resolved spatially; they are not necessarily different to each other in Bragg wavelength. By sweeping the center frequency of the light source in a sawtooth waveform, the shape of the FBG reflection spectrum can be obtained, and thus the amount of the strain applied to the FBG can be estimated. Up to date, 100-Hz interrogation speed was achieved with this method, and the measurement range is limited to within the coherence length of the light source. In this presentation, novel methods are proposed to enhance the interrogation speed and the measurement range further. The performance-limiting factors on the interrogation speed and the measurement range are evaluated. It is found that the detected interference signal appears at a certain frequency shifted from the heterodyne beat due to the sweeping of the center frequency. By observing at the shifted frequency, 1-kHz interrogation speed and measurement range beyond coherence length of the light source are achieved.

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Section: Performance Limiting Factor and Its Solutionsmentioning

confidence: 86%

“…2. 5 It consists of an interference system between the reference light and the reflection light from FBGs. The interference is observed by using the heterodyne detection.…”

Section: Principle Of Multiplexed Fbg Strain Sensor By Socfmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Basic setup for multiplexing FBGs with the same Bragg wavelength by the synthesis of optical coherence function 5. …”

mentioning

confidence: 99%

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High-speed interrogation of multiplexed fiber Bragg grating sensors with similar Bragg wavelength by synthesis of optical coherence function

Hayashi

Hotate

2005

Fiber Optic Sensor Technology and Applications IV

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“…In this work, we present the result of a numerical simulation to shape the temporal coherence function (TCF) by destructive overlapping of the spectra of different self-phasemodulated Gaussian pulses obtained by propagating through different lengths of nonlinear fibers. Coherence shaping by synthesis of light-emitting diodes [7], by optimal spectral reshaping of a single light source [8], and by a frequencymodulation technique [9] have been reported. Recently, spatial coherence function control using the spatial distribution of a single-wavelength light source has also been proposed, demonstrated, and applied [10]- [12].…”

Section: Introductionmentioning

confidence: 99%

Temporal coherence shaping based on spectral-domain destructive interference of pulses with different self-phase modulations

Wei

Takamasu

Matsumoto

2013

J. Eur. Opt. Soc.-Rapid Publ.

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We show via a numerical simulation that the temporal coherence function (TCF) can be shaped by the destructive interference of pulses characterized by different amounts of self-phase modulation (SPM) in the spectral domain. We find that pulse spectra destructively interfering with one another can yield a TCF with distinct peaks. Numerical investigation demonstrates that the shape of the TCF is changeable not only by broadening the spectrum but also by overlapping spectra of the pulses that have experienced different amounts of SPM.

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Expansion of spatial measurement range by use of vernier effect in multiplexed fibre Bragg grating strain sensor with synthesis of optical coherence function

Enyama

Hotate

2005

Meas. Sci. Technol.

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Adopting a technique named synthesis of optical coherence function (SOCF), we have recently published a system of multiplexed fibre optic sensors with fibre Bragg gratings (FBGs) which may have similar Bragg wavelengths to each other (Hotate et al 2004 Meas. Sci. Technol. 15 148–53, Hotate and Enyama 2003 Proc. 16th Int. Conf. Optical Fiber Sensors (Nara, Japan) pp 522–5). In that system, the coherence function is synthesized into a series of periodical peaks that can be scanned along the fibre. By using one of the peaks as a measurement window, and sweeping it along a string of FBGs, the FBGs can be spatially resolved. To avoid the error signal from coherence peaks other than the designated measurement window, the string of FBGs has to be arranged within one period of the coherence peaks, i.e., the spatial measurement range of the system is limited to one period of the coherence function. In this paper, we propose a novel scheme that uses multiple coherence peaks to detect multiple FBGs. The coherence peaks and FBGs are arranged with the vernier effect, which means the period of the coherence function is slightly different from the interval of the FBGs, so at any moment, only one FBG can meet a coherence peak. In this way, the limitation to the measurement range is solved.

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Dynamic and random-access strain measurement by fiber Bragg gratings with synthesis of optical coherence function

Cited by 12 publications

References 4 publications

High-speed interrogation of multiplexed fiber Bragg grating sensors with similar Bragg wavelength by synthesis of optical coherence function

High-speed interrogation of multiplexed fiber Bragg grating sensors with similar Bragg wavelength by synthesis of optical coherence function

Temporal coherence shaping based on spectral-domain destructive interference of pulses with different self-phase modulations

Expansion of spatial measurement range by use of vernier effect in multiplexed fibre Bragg grating strain sensor with synthesis of optical coherence function

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