Multiplexing of optical fiber sensors using a frequency-modulated source and gated output

Sakai, I.; Youngquist, Robert C.; Parry, G.

doi:10.1109/jlt.1987.1075586

Cited by 35 publications

(30 citation statements)

References 14 publications

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“…Unfortunately, it is very difficult to implement sensor multiplexing for many conventional sensors. One exception is the optical fiber sensors, which can be multiplexed based on various multiplexing mechanisms, including time-domain multiplexing (TDM) 13 , wavelength-domain multiplexing (WDM), frequency-domain multiplexing (FDM) 14 , combination of both TDM and WDM 15 , and coherence multiplexing. However, if the optical fiber sensors are multiplexed in series, damaging the optical fiber at one location will disable all the downstream sensors.…”

Section: Introductionmentioning

confidence: 99%

Multiplexing wireless antenna sensors for crack growth monitoring

Huang

2011

SPIE Proceedings

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This paper presents the multiplexing of unpowered wireless antenna sensors for crack monitoring at multiple locations. Four antenna sensors were multiplexed to form a sensor array based on two multiplexing principles, namely frequency division and spatial division. For frequency division, a dual-antenna sensor array with each sensor operating at different frequencies was designed and implemented. Simultaneous interrogation of these two sensor elements has been achieved. For spatial division, two single antenna sensors with the same resonant frequencies as the dual-antenna sensor array were installed at different locations. By steering the illumination light toward their wireless impedance-switch circuits, these two single antenna sensors can be interrogated individually. The capability of the antenna sensor array to monitor multiple crack growth in a fatigue specimen was evaluated. Compared to a single antenna sensor, the antenna sensor array enables us to track the status of cracks over a large area.

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Section: Introductionmentioning

confidence: 99%

Multiplexing wireless antenna sensors for crack growth monitoring

Huang

2011

SPIE Proceedings

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“…By using (7) and (lo), (11) can be rewritten as (13) where the superscripts "s" and "T" on A" and AI, a and R refers to the corresponding constants to the sensors and readout cavities. In order to evaluate (13) …”

Section: Pmdi With High Finesse Fabry-perot Read-out Interferometersmentioning

confidence: 99%

“…Also, the wavelength modulation utilizing a diode laser requires that the path imbalances of the sensors be on the order of a centimeter long for sufficient depth of modulation to be produced without inducing mode-hopping in the laser [ 121. A sinusoidal modulation-based frequency division multiplexing was used by Sakai et al [13] who used a single frequency gas laser and an external PZT modulator to produce a Doppler wavelength-induced wavelength modulation. This narrow-linewidth single mode laser with an external phase modulator avoids the nonlinearity of current modulation of diode lasers; however, sensor path imbalances on the order of meters are required to achieve depths of modulation sufficient for frequency division multiplexing.…”

Section: Introductionmentioning

confidence: 99%

Multiplexed optical fiber sensors using a single Fabry-Perot resonator for phase modulation

Chang

Sirkis

1996

J. Lightwave Technol.

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Abstruct-This paper describes the use of different optical return paths in a single Fabry-Perot phase modulator to perform coherence division multiplexing, and a combination of coherence and frequency division multiplexing of Fabry-Perot interferometric optical fiber sensors. A path-matched differential interferometry (PMDI) using low finesse Fabry-Perot sensors, one moderate finesse Fabry-Perot read-out resonator, and a broadband light source consisting of amplified spontaneous emission (ASE) from an erbium-doped fiber amplifier (EDFA) is used to illustrate the idea. The first, second and third order of multiple paths in a single Fabry-Perot read-out resonator are used to path-match three Fabry-Perot sensors. These three orders of path-matches provide a single, double and triple depth of modulation (phase-change) when the read-out is used as an optical phase modulator, and therefore provide a single, double and triple carrier frequency when serrodyne demodulation is used. The use of a single moderate finesse read-out Fabry-Perot resonator to simultaneously path-match coherence multiplexed sensors reduces the complexity of the optical system. Experiments and modeling are used to show the existence of the first, second, and third order of interference path-match conditions, and to determine the read-out configuration that enhances the visibility of the higher order path-match conditions. Using the multiple return paths in a single PZT-based Fabry-Perot read-out interferometer and serrodyne demodulation, several multiplexing schemes are investigated, and their relative merits discussed.

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“…In recent years, FMCW technique has been developed for multiplexing intensity-based [16] and interferometer fiber optic sensors [17,18]. In this case the performances of the system are strongly dependent on the appropriate design of electronic filters, which have to be trimmed on the sensor point locations.…”

Section: Introductionmentioning

confidence: 99%