Cavity Ring-Down with OTDR for remote sensing

Abstract

This work presents a demonstration of the potential of fiber cavity ring-down for remote sensing, by using an OTDR to send impulses down similar to 20 km of optical fiber at the end of which the fiber ring cavity was placed. The OTDR showed almost no losses in the fiber, so other ring-down cavities could be spliced along the same fiber. To study the sensitivity of the cavity ring an intensity sensor based on a taper was placed in the ring and glued to a translation stage. A displacement of the stage imposes a curvature on the taper and an associated loss. The configuration had a sensitivity of (11.8 +/- 0.5) mu s/mm.