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Dynamic strain measured by Mach-Zehnder interferometric optical fiber sensors.

Her SC, Yang CM - Sensors (Basel) (2012)

Bottom Line: Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent.A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer.The experimental results are validated with the strain gauge.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Yuan Ze University, Chung-Li 320, Taiwan. mesch@saturn.yzu.edu.tw

ABSTRACT
Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent. In this investigation, a Mach-Zehnder interferometric optical fiber sensor is used to measure the dynamic strain of a vibrating cantilever beam. A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer. The dynamic strain of a cantilever beam subjected to base excitation is determined by the optical fiber sensor. The experimental results are validated with the strain gauge.

No MeSH data available.


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Mach-Zehnder interferometer.
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f1-sensors-12-03314: Mach-Zehnder interferometer.

Mentions: The schematic diagram of a Mach-Zehnder interferometer is shown in Figure 1. It consists of two 2 × 2 couplers at the input and output. The excitation is applied to the sensing fiber, resulting optical path difference between the reference and sensing fibers. The light intensity of the output of the Mach-Zehnder interferometer can be expressed as [19]:(1)I=2A2(1+cosΔϕ)Δϕ=2πn0λ{1−n02[(1−v)P12−vfP11]}∫Lf εf dxwhere Δϕ is the optical phase shift; n0 is the refractive index of the optical fiber; λ is the optical wavelength, vf is the Poisson’s ratio; P11 and P12 are the Pockel’s constants; Lf and εf are the length and strain of the optical fiber, respectively. Since the terms in front of the integral sign of Equation (1) are constants for any given optical fiber system, the total optical phase shift Δϕ is proportional to the integral of the optical fiber strain. By measuring the total optical phase shift, the integral of the optical fiber strain can be easily obtained as follows:(2)∫ΓSεf dx=Δϕ2πn0λ{1−12n02[(1−vf)P12−vfP11]}


Dynamic strain measured by Mach-Zehnder interferometric optical fiber sensors.

Her SC, Yang CM - Sensors (Basel) (2012)

Mach-Zehnder interferometer.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376560&req=5

f1-sensors-12-03314: Mach-Zehnder interferometer.
Mentions: The schematic diagram of a Mach-Zehnder interferometer is shown in Figure 1. It consists of two 2 × 2 couplers at the input and output. The excitation is applied to the sensing fiber, resulting optical path difference between the reference and sensing fibers. The light intensity of the output of the Mach-Zehnder interferometer can be expressed as [19]:(1)I=2A2(1+cosΔϕ)Δϕ=2πn0λ{1−n02[(1−v)P12−vfP11]}∫Lf εf dxwhere Δϕ is the optical phase shift; n0 is the refractive index of the optical fiber; λ is the optical wavelength, vf is the Poisson’s ratio; P11 and P12 are the Pockel’s constants; Lf and εf are the length and strain of the optical fiber, respectively. Since the terms in front of the integral sign of Equation (1) are constants for any given optical fiber system, the total optical phase shift Δϕ is proportional to the integral of the optical fiber strain. By measuring the total optical phase shift, the integral of the optical fiber strain can be easily obtained as follows:(2)∫ΓSεf dx=Δϕ2πn0λ{1−12n02[(1−vf)P12−vfP11]}

Bottom Line: Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent.A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer.The experimental results are validated with the strain gauge.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Yuan Ze University, Chung-Li 320, Taiwan. mesch@saturn.yzu.edu.tw

ABSTRACT
Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent. In this investigation, a Mach-Zehnder interferometric optical fiber sensor is used to measure the dynamic strain of a vibrating cantilever beam. A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer. The dynamic strain of a cantilever beam subjected to base excitation is determined by the optical fiber sensor. The experimental results are validated with the strain gauge.

No MeSH data available.


Related in: MedlinePlus