Date of Award

Summer 2001

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical & Computer Engineering

Program/Concentration

Electrical Engineering

Committee Director

Sacharia Albin

Committee Member

Linda L. Vahala

Committee Member

Vijayan Asari

Call Number for Print

Special Collections LD4331.E55 B46 2001

Abstract

Fiber Bragg gratings are periodic modulations of the refractive index of the fiber core exhibiting strong reflection at specific wavelengths determined by the periodicity and magnitude of the index modulation. Due to elastic and thermo optic properties of glass, the Bragg wavelength is sensitive to temperature and axial strain. The inability to discriminate between the effects of temperature and strain on fiber Bragg gratings, however, limits their use in sensing applications. Several schemes have been proposed to overcome this problem, and one involving a dual wavelength Bragg grating sensor implemented with co-located 850 nm and 1550 nm gratings is investigated. Calibration curves for the temperature and strain responses of the sensor grating where made experimentally. Based these curves, errors of less than I' and 2 Its are predicted. When subjected to simultaneous temperature and strain fields, errors of up to 130' and 1700 Its were encountered. The discrepancy is traced to the use of a refraction grating based optical spectrum analyzer, an accepted piece of test equipment in Bragg grating sensor research, as a wavelength standard, which introduces an unacceptable degree of random error as a result of its limited resolution and repeatability in practical applications.

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DOI

10.25777/6mfz-hw54

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