Digital spectral analysis and adaptive processing techniques for phase modulated optical fiber sensors

The objective of this work is to investigate new signal processing techniques for optical fiber sensors that utilize the phase information of the electromagnetic field. Research concentrated on Fourier transform spectroscopy as a means for capturing wavelength encoded information from the fiber sensor. Classical spectral analysis utilizing the Fourier transform as a mathematical foundation for relating a time or space signal to its frequency-domain representation was shown to be inadequate for mitigating the bias errors caused by harmonic distortions. A modified spectral estimation algorithm is presented to overcome some of the practical issues while maintaining the high spectral resolution characteristic of the classical technique. This research also showed that unlike in free-space propagation, an optical signal propagating through a fiber waveguide, even over short distances, can experience significant phase modulation noise. A number of chromatic distortion mechanisms including modal interference, mode coupling due to periodic perturbations such as microdeformation and macrobends, and mode field diameter variations are addressed. We treated these issues by employing both theoretical simulation and experimental data. Coupled-mode formalism based upon approximated field solutions is used in the theoretical analysis. An extensive error analysis was also performed to determine how waveguide and noise distortion affect the performance of the spectral estimation algorithm.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Electrical Engineering

Department dc:contributor.department

Electrical Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1996

Author dc:creator

• Tran, Tuan A.

Chair dc:contributor.committeechair

• Murphy, Kent A.

Committee members dc:contributor.committeemember

• Claus, Richard O.
• VanLandingham, Hugh F.
• Besieris, Ioannis M.
• Heflin, James R.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-11102005-141134

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/40328