Optical waveguides – Optical waveguide sensor
Patent
1997-09-30
1999-11-16
Ngo, Hung N.
Optical waveguides
Optical waveguide sensor
385 24, G02B 626
Patent
active
059871954
ABSTRACT:
The fiber optics sensor includes a polarization maintaining optic fiber forming an optical loop, and a sensing medium coupled to the optic fiber and disposed generally midway in the optical loop. First and second quarter waveplates, coupled to the optic fiber and oriented at approximately 45.degree. with one another in close proximity to the sensing medium, convert two counter-propagating linearly polarized light waves traveling in the optical loop into two counter-propagating circularly polarized light waves prior to passing through the sensing medium. The first and second quarter waveplates further convert the counter-propagating circularly polarized light waves into two linearly polarized light waves after exiting the sensing medium. The counter-propagating circularly polarized light waves passing through the sensing medium experience a differential phase shift caused by a magnetic field or current flowing in a conductor proximate to the sensing medium. A detector is coupled to the optic fiber and detects the differential phase shift and produces an output in response thereto.
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Ngo Hung N.
The Texas A&M University System
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