Distributed gas detection along microstructured optical fibers through photothermal absorption

Abstract

Chirped-pulse phase-sensitive optical time domain reflectometry has shown a remarkable performance when applied to dynamic measurements of strain and temperature, recently reaching ranges of several kilometers while interrogating the fiber at acoustic frequencies. In this work, its sensitivity, fast response, and high spatial resolution are exploited to demonstrate the reliability of a selective distributed chemical sensor based on the photothermal effect. The presented scheme performs distributed spectroscopic detection of acetylene along a holey fiber. This potentially gives rise to a new kind of distributed chemical sensors able to track the concentration of chemical species over kilometres.