Precision time domain reflectometry in optical fiber systems using a frequency modulated continuous wave ranging technique

This paper describes a novel optical time domain reflectometer which uses a frequency-modulated single-mode semiconductor laser as the optical source. The new system offers a potential distance resolution of the order of 1 mm over ranges limited by the source linewidth. In this paper, a theoretical assessment of the features which determine the available performance of the system is followed by some experimental results which confirm these general trends. Applications of this system include short range fault location in situations where resolution of the order of centimeters is required, and as a novel discrimination technique for optical sensor multiplexing systems.