Interferometric optical time-domain reflectometry for distributed optical fiber sensing

Abstract

The technique of optical-time domain reflectometry (OTDR) is analyzed to determine the effect of an optical phase modulation on light backscattered in an optical fiber. It is shown that the spatial distribution, along the fiber, of an external phase modulation can be measured with a spatial resolution close to that of the OTDR. A distributed interferometric sensor arrangement employing this technique has been investigated experimentally, and a satisfactory interrogation of more than one thousand resolution intervals has been demonstrated.