Distributed Sensing of Single Mode Fibers with Correlation Techniques

TL;DR

This paper advances correlation-based optical time domain reflectometry by integrating coherent detection, which enhances sensitivity and allows phase and polarization analysis of reflections in single-mode fibers.

Contribution

The paper introduces a coherent detection scheme for correlation OTDR, improving sensitivity and enabling phase and polarization measurements compared to traditional methods.

Findings

Coherent detection improves sensitivity over direct detection.

Phase and polarization information can be extracted from reflected signals.

Enhanced resolution in spatial and amplitude measurements.

Abstract

In this paper, we report on the development progress of correlation-based optical time domain reflectometry (OTDR). Substituting the direct detection receiver with a coherent receiver enables to extract the phase and polarization information of the reflected signal. Furthermore, due to the mixing of a weak probe signal with a strong local oscillator the sensitivity of the receiver improved. This improvement was demonstrated by analyzing the reflection from an angled physical contact (APC) connector. To further quantify the improvements, we compare the direct detection correlation OTDR (C-OTDR) with the coherent detection correlation OTDR (CC-OTDR) with respect to the spatial and amplitude resolution.