A study of optical frequency domain reflectometry and its associated distributed sensor applications

Abstract

Optical Frequency Domain Reflectometry (OFDR) is an interferometric technique which is capable of interrogating fibers under test (FUT) up to kilometers in length with millimeter resolution[10]. It does so by taking the Rayleigh backscattered light, or Fresnel back-reflected light and combining it with the reference arm to create a beating signal. The beating signal is then Fourier transformed to create a scattering profile of the FUT. Presented in this thesis are 5 novel OFDR configurations that improve the SNR in the spatial domain up to 26dB. As well, 4 new data analysis algorithms are presented that improve the spectral resolution by up to a factor of 40 and spectral SNR by 1.31dB. The FUT's investigated are regular SMF, linear FBG's, and chirped FBG's. With these, the wavelength shift at specific points along the FUT is measured and correlated with temperature changes (with associated applications), longitudinal stress, and torsional stress stimuli.