Multimode excitation-induced phase shifts in intrinsic Fabry–Perot interferometric fiber sensor spectra

Ma, Cheng; Wang, Anbo

doi:10.1364/ao.49.004836

Cited by 8 publications

(7 citation statements)

References 22 publications

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“…Intuitively, the greater the distortion is, the larger the phase term; as the distortion is OPD-dependent, so is the induced phase. For EFPIs, detailed analysis can be found in [25,33,34], and the case for IFPIs was studied in [35]. In general, for an EFPI, the phase term caused by wave front distortion is small and changes moderately with OPD; for an IFPI, due to multimode excitation, this term could be large and change more rapidly.…”

Section: Wave Front Distortionmentioning

confidence: 99%

Signal processing of white-light interferometric low-finesse fiber-optic Fabry–Perot sensors

Wang

2013

Appl. Opt.

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Signal processing for low-finesse fiber-optic Fabry-Perot sensors based on white-light interferometry is investigated. The problem is demonstrated as analogous to the parameter estimation of a noisy, real, discrete harmonic of finite length. The Cramer-Rao bounds for the estimators are given, and three algorithms are evaluated and proven to approach the bounds. A long-standing problem with these types of sensors is the unpredictable jumps in the phase estimation. Emphasis is made on the property and mechanism of the "total phase" estimator in reducing the estimation error, and a varying phase term in the total phase is identified to be responsible for the unwanted demodulation jumps. The theories are verified by simulation and experiment. A solution to reducing the probability of jump is demonstrated.

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Section: Wave Front Distortionmentioning

confidence: 99%

Signal processing of white-light interferometric low-finesse fiber-optic Fabry–Perot sensors

Wang

2013

Appl. Opt.

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“…The spectrum of the SMS-IFPI, normalized with respect to the input power, is expressed as [19]   where R is the reflectivity of the splicing point and L is the length of the FP cavity. For WLI based signal demodulation, the optical path difference (OPD), defined as…”

Section: The Spectrum Of Gi-mmf Based Ifpimentioning

confidence: 99%

“…Non-constant phase-induced OPD demodulation jumps To interrogate a low-finesse FP sensor, the phase of the periodic fringe pattern is measured at either a fraction or all of the sampling points in the spectrogram [20,21,22,23]. This interference spectrum is represented by S(k)  cos[Φ(k)], where k=2π/λ is the optical wavenumber, λ is the wavelength, Φ(k) is the total interferogram phase which is expressed as Φ(k) = k  OPD + φ 0 , where φ 0 is an additional phase term caused by beam reflection and propagation [19,24]. In traditional OPD-based demodulation, the additional phase term φ 0 is usually assumed to be constant during measurement process and needs to be pre-calibrated [21,22].…”

Section: Sensor Signal Processing and The Total Phase Approachmentioning

confidence: 99%

“…In traditional OPD-based demodulation, the additional phase term φ 0 is usually assumed to be constant during measurement process and needs to be pre-calibrated [21,22]. However, physical changes in IFPI sensors can cause this term to vary during measurement (as discussed in Section 3.3.1, and in Ref [19,24] The SMS-IFPI sensors were typically interrogated using a swept-laser interrogation system (Micron Optics Si-720) over a spectral range of 1520-1570nm with spectral resolution of 2.5pm, dynamic range of 70dB, and a scanning rate of 0.5Hz. Each collected spectrum was subsequently processed using a peak tracking method, in which local curve fitting is used to identify the exact locations of every fringe peak in the interferogram, and their corresponding fringe orders are determined to measure OPD [20, 21,23].…”

Section: Sensor Signal Processing and The Total Phase Approachmentioning

confidence: 99%

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Multiplexed Optical Fiber Sensors for Coal Fired Advanced Fossil Energy Systems

Wang¹,

Pickrell²

2012

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This three-year project started on October 1, 2008. In the project, a fiber optical sensing system based on intrinsic Fabry-Perot Interferometer (IFPI) was developed for strain and temperature measurements for Ultra Supercritical boiler condition assessment. Investigations were focused on sensor design, fabrication, attachment techniques and novel materials for high temperature and strain measurements.At the start of the project, the technical requirements for the sensing technology were determined together with our industrial partner Alstom Power. As is demonstrated in Chapter 4, all the technical requirements are successfully met. The success of the technology extended beyond laboratory test; its capability was further validated through the field test at DOE NETL, in which the sensors yielded distributed temperature mapping of a testing coupon installed in the turbine test rig. The measurement results agreed well with prior results generated with thermocouples.In this project, significant improvements were made to the IFPI sensor technology by splicing condition optimization, transmission loss reduction, sensor signal demodulation and sensor system design. These innovations have yielded three journal publications and two conference papers.

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“…While it is well understood that the demodulation error scales with noise power in the spectrum [10], the demand for high fringe visibility becomes crucial, especially if a multimode fiber (MMF) is used for excitation. During the past few years, it has been reported in several publications [8,11,12] that the additional phase in the spectrum also plays an important role in signal processing, which may potentially lead to abrupt jumps in the demodulated sensor cavity length. As such, in-depth theoretical modeling for both single-mode fiber (SMF) and MMF based EFPIs have been investigated in the past two decades [8,[13][14][15], aiming to find the dependence of sensor output spectrum on sensor geometry and optical property.…”

Section: Introductionmentioning

confidence: 99%

Decoding the spectra of low-finesse extrinsic optical fiber Fabry-Perot interferometers

Ma¹,

Dong²,

Gong³

et al. 2011

Opt. Express

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A theoretical model is developed to address the fringe visibility and additional phase in the interference spectra of low-finesse extrinsic optical fiber excited Fabry-Pérot interferometers. The model described in the paper applies to both single-mode and multimode fiber excitations; according to the theory, the fringe visibility and additional phase term are primarily determined by the working wavelength and angular power density distribution outputting from the excitation fiber, rather than based on spatial and temporal degree of coherence. Under certain approximations, the output interference intensity and the spatial power density distribution projected onto the fiber axis form a Fourier-transform pair, which potentially provides a tool for spatial density distribution analysis of fiber output. With excellent agreement with experiments, the theory presented in this paper leads to design guidelines for Fabry-Pérot interferometric sensors and insightful physical understanding of such devices. Interferometric Optical Fiber Sensor Using Kirchhoff's Diffraction Formalism," Opt. Fiber Technol. 1(4), 380-384 (1995). 14. F. Pérennès, P. C. Beard, and T. N. Mills, "Analysis of a low-finesse Fabry-Perot sensing interferometer illuminated by a multimode optical fiber," Appl. Opt. 38(34), 7026-7034 (1999 Optical Society of America. Cheng Ma, Bo Dong, Jianmin Gong, and Anbo Wang, "Decoding the spectra of low-finesse extrinsic optical fiber Fabry-Perot interferometers," Opt. Express 19, 23727-23742 (2011 ©2011 Optical Society of America

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Multimode excitation-induced phase shifts in intrinsic Fabry–Perot interferometric fiber sensor spectra

Cited by 8 publications

References 22 publications

Signal processing of white-light interferometric low-finesse fiber-optic Fabry–Perot sensors

Signal processing of white-light interferometric low-finesse fiber-optic Fabry–Perot sensors

Multiplexed Optical Fiber Sensors for Coal Fired Advanced Fossil Energy Systems

Decoding the spectra of low-finesse extrinsic optical fiber Fabry-Perot interferometers

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