Current sensors using highly birefringent bow-tie fibres

Li, L.; Qian, Jingren; Payne, D.N.

doi:10.1049/el:19860783

Cited by 46 publications

(15 citation statements)

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“…The intensity of the two orthogonal polarisation states, I1 and I2 were measured and electronically processed to obtain the ratio I1-I2 1 + cosR I1+I2 2 sin2(c-tz) (7) We recall that from the previous discussion the required temperature-independent condition is met when R =O, at which point the rotation S2 = tz and the ratio in equation (7) passes through zero.…”

Section: Methodsmentioning

confidence: 99%

Current Monitor Using Elliptical Birefringent Fibre And Active Temperature Compensation

Laming

Payne

1987

Fiber Optic Sensors II

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Highly -elliptically birefringent fibres have been obtained by spinning a linearlybirefringent fibre during the draw. These fibres are particularly interesting for use in Faraday-effect fibre current monitors, since, in contrast with conventional fibres, they can be wound in small multi -turn coils and retain their sensitivity. We show that here the fibre output state of polarisation can be controlled to compensate for environmental perturbations using only one remote active element. Using a compact 80 -turn fibre coil, currents up to 370 A rms have been measured, with a maximum sensitivity of 100NA rms Hz-.

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Section: Methodsmentioning

confidence: 99%

Current Monitor Using Elliptical Birefringent Fibre And Active Temperature Compensation

Laming

Payne

1987

Fiber Optic Sensors II

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“…Unfortunately, variations in stress and temperature of the sensing fiber may change the distribution of linear birefringence in the fiber, which alter the polarization of light in the fiber and degrade sensor system's measurement accuracy [1]. In order to reduce the influence of temperature and external stresses, it is desirable to make the sensing fiber with high circular birefringence or low linear birefringence, for example, the spun fiber [1][2][3][4], the annealed fiber [5,6], the low-stress fiber [7], or the helically wrapped fiber [8]. Among the various fibers, the spun fiber is better accepted in the industry [3] for its manufacturability and high sensing accuracy over a wide range of environmental conditions, including temperature and vibration, making it suitable for current sensors deployed in both indoors and outdoors in real-life applications.…”

Section: Introductionmentioning

confidence: 99%

“…A spun fiber can be fabricated by first making a preform with two stress rods similar to that for making a linear polarization maintaining fiber (e.g. a bow-tie fiber or a PANDA fiber), and then spinning the perform during drawing in the molten state [4]. The spinning process induces a large circular birefringence and significantly reduces the average linear birefringence over distance, although the local linear birefringence still remains strong [4] to overcome the stress and temperature induced birefringence perturbations.…”

Section: Introductionmentioning

confidence: 99%

“…a bow-tie fiber or a PANDA fiber), and then spinning the perform during drawing in the molten state [4]. The spinning process induces a large circular birefringence and significantly reduces the average linear birefringence over distance, although the local linear birefringence still remains strong [4] to overcome the stress and temperature induced birefringence perturbations. It is important to have the detailed knowledge of the circular and the residual total linear birefringences of the spun fiber, particularly their temperature dependences, to ensure that the current sensing system incorporating the fiber is insensitive to temperature variations and external stresses and eventually meets its performance requirements.…”

Section: Introductionmentioning

confidence: 99%

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Accurate measurements of circular and residual linear birefringences of spun fibers using binary polarization rotators

Xu¹,

Yao²,

Ding³

et al. 2017

Opt. Express

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We present a method to accurately measure the birefringence properties of spun fibers using binary polarization rotators. By taking the advantages of binary polarization rotator in polarization analysis, we are able to simultaneously measure both the circular and linear birefringences in a spun fiber with high accuracy. We obtain the circular and the residual linear birefringences of the spun fiber as a function of temperature T to be 3.34 × 10-5.11 × 10T and 8.1 × 10-1.19 × 10T, respectively, with the residual linear birefringence about 4 times less than the circular birefringence. We find, for the first time with the best of authors' knowledge, that the circular and the residual linear birefringences in a spun fiber are highly linear with the temperature, with thermal coefficients of -5.11 × 10 °C and -1.19 × 10°C, respectively, and that the relative changes per °C of the circular and residual linear birefringence are almost identical, with values of -0.152% and -0.147% respectively. We believe that the method and data presented in this paper will be beneficial for making high quality spun fibers, as well as high accuracy fiber optic current sensors.

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“…Operation of most of these fiber optic current sensors is based on the Faraday effect. [1][2][3] When linearly polarized light propagates through an optically active medium, the plane of polarization rotates under the influence of an external electromagnetic field. The magnitude of this rotation is proportional to the material's Verdet constant ͑degree of rotation per unit magnetic field strength per unit length of the medium͒, and magnitude of the electrical current's magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Differentiating fiber optic reflective ring interferometer for alternating current measurements

Swart

Spammer²

1996

Opt. Eng

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A differentiating interferometer is proposed for measuring time varying signals. The system comprising a modified fiber ring resonator was implemented to measure electrical current. The ring interferometer consists of a length of fiber between one of the input and output ports of a directional coupler. This length of fiber forms a delay line resulting in a constant delay time. The other coupler output port is connected to the sensing element and a reflector. By virtue of the time delay the system detects the derivative of the unknown perturbation signal at the common input/output port of the interferometer. This configuration ensures a zero path length imbalance. Electrical current measurements are achieved by means of a current transformer terminated with a resistive load, which drives a piezoelectric phase modulator. The interferometer can be optically biased by a polarization controller to measure differential phase linearly over the range Ϫ/2 to /2 rad. An integration function yields the unknown electrical current. By employing a directional coupler in the system another reflective interferometer arm can be formed for multiplexed operation. The introduction of frequency domain demultiplexing allows interrogation of the sensors in each of these arms. Different phase generated carriers are applied to each arm with two additional piezoelectric phase modulators. Synchronous and quadrature phase detection yield the two current signals. Results of current measurements between 9 A and 300 A on two 50 Hz phases are discussed for the optically biased and phase generated carrier configurations.

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Current sensors using highly birefringent bow-tie fibres

Cited by 46 publications

References 1 publication

Current Monitor Using Elliptical Birefringent Fibre And Active Temperature Compensation

Current Monitor Using Elliptical Birefringent Fibre And Active Temperature Compensation

Accurate measurements of circular and residual linear birefringences of spun fibers using binary polarization rotators

Differentiating fiber optic reflective ring interferometer for alternating current measurements

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