Polarimetric strain gauges using high birefringence fibre

Tbeoretical and experimental results on birefringent optical fibers embedded in concrete are presented and discussed. We study the effect of strain on the propagation of light in birefringent fibers embedded in a host material loaded under uniform compression. Both longitudinal and transverse deformations are considered in the analysis since the fiber is embedded along a direction perpendicular to the strain load. The effects of the strain on the birefringence of the fiber and the rotation of the optical axes are studied. The theoretical model is used to determine the best polarimetric system configuration to detect strain. Our experimental work was performed by embedding optical fibers in standard concrete cylinders, attaching resistive electric strain gauges on the surface, and testing the specimens under uniform compressive stress. Optical transmission data from the fiber and readings from the electric strain gauges were simultaneously recorded.

Section: Optical Transmissionsupporting

confidence: 82%

“…The output power after passing through the polarizer or p2 is E: PI = -[cos2 y + a2 sin2 y + a sin 27 cos(q5 + C ) ] y + a2 cos2 y -a sin 27 cos(q5 + C)](25) whereC = (Os/ -Pf! )L(l+ t z e x 2 )…”

mentioning

confidence: 99%

Theory and experiments on birefringent optical fibers embedded in concrete structures

Calero

Pope

et al. 1994

“…As an example, with P44 = -0.072 and n = 1.46 for silica glass, we find from (5) For a fiber with a beat length of 2.4 mm, if we take ( a 2 -a l ) T = -1 x v2 -v1 = 0.02 [12], and vo = v1 = v2 = 0.2, we find from (9) 0 . 0 3~…”

Section: Ultrasonically Induced Birefringencementioning

confidence: 93%

“…We ignore the small effect due to the variation of E in the fiber by assuming a constant E in (6). We consider only the larger effect due to the variation of v in the fiber and thus assume v = v1 in the cladding and v = v2 in the stress-applying regions with v2 slightly larger than v1 [12]. According to (6), the stress-applying regions and the surrounding cladding are strained differently.…”

Section: B Isotropic Regimementioning

confidence: 99%

Detection of high-frequency ultrasound with a polarization-maintaining fiber

Chiang

Chan

Gardner

1990

Abstruct-The effect of a high-frequency ultrasonic wave incident normally upon a polarization-maintaining optical fiber is investigated theoretically and experimentally. Two different mechanisms accounting for the change of the birefringence in the fiber due to the radial strain produced by the ultrasonic wave are identified and studied. The more well-known mechanism, which also occurs in a single-mode fiber, arises from the anisotropic strain distribution in the fiber, and is significant only at very high frequencies. The other mechanism, which occurs only in a polarization-maintaining fiber, arises from the inhomogeneous elastic properties of the fiber, and is more significant than the former mechanism at lower frequencies. Because of the latter effect, a polarization-maintaining fiber can respond to lower frequencies than a single-mode fiber in the polarimetric mode. The frequency that separates the ranges of significance of these two mechanisms is experimentally found to be about 1 MHz (in water). The principle and the realization of a polarimetric ultrasonic sensor using a polarizationmaintaining fiber are also described.

“…IEEE Log Number 8609528. the application of an axial strain [3]. In bow-tie fibers, this is due to the Poisson's ratio mismatch in the component glasses of the fiber [4]. The phase delay per unit fiber length per unit strain is defined as the responsivity 11.…”

Section: Polarimetermentioning

confidence: 99%

Fiber-optic polarimetric DC magnetometer utilizing a composite metallic glass resonator

Mermelstein¹

1986

A fiber-optic polarimetric dc magnetometer has been constructed from 50 m of high birefringence optical fiber. Magnetic fields are detected by the magnetostrictive response of a composite thin-shell resonator consisting of an acrylic tube, unannealed metallic glass ribbon, and a 20-m coil of high birefringence fiber. Quadrature is maintained with the phase tracking technique and optical common-mode rejection is utilized for noise reduction. The rms magnetometer noise corresponds to a minimum detectable magnetic field of 2.6 y in the dc to 1-Hz bandwidth.