<title>Fiber optic multiplex sensing: resolution enhancement in optical time domain reflectrometry through novel signal processing</title>

Abstract

Optical time domain reflectometry (OTDR) is a versatile technique that enables loss measurement and fault location. Such an information is essential in the design of a good fiber optic communication system. A high resolution OTDR is also necessary in distributed fiber optic sensor systems, where the distance between sensors is limited by the achievable OTDR resolution. Improved resolution in OTDR is generally realized using pulses of shorter width (typically in the picosecond range). However, such systems are more expensive. In this paper, we present a novel signal processing technique based on inverse spiking filter to improve the resolution of an OTDR system. In addition, we present experimental verifications of the resolution enhancement achieved for a nanosecond pulse with an OTDR system configured by us. The minimum length of the second fiber (butt coupled to a parent fiber of length about half a kilometer) that could be resolved using a deconvolution technique was 1.5 metres. This method has great potential not only for detecting splice locations accurately but also for distributed sensor configurations.