Transmission-Reflection Analysis in high scattering optical fibers: A comparison with single-mode optical fiber

Transmission-Reflection Analysis (TRA) is an inexpensive technique used in distributed monitoring systems for single perturbation tracking. However, TRA is limited to long distance applications (similar to km), since it has poor spatial resolution (similar to m) when combined to standard silica fibers. This paper proposes the use of a magnesium and erbium co-doped optical fiber in conjunction with the TRA technique. The goal is to improve spatial resolution and accuracy for detection of loss-inducing disturbances along the sensing fiber. Bending losses are induced at several points of the fiber spaced at 50 cm over a 5.4 m fiber length, where each curve is clearly identified with a maximum hysteresis of 1.65%. The localization of a strong disturbance with an estimated accuracy of +/- 0.8 mm near the source end and +/- 7.2 mm near the fiber end is analytically demonstrated. Regarding weak disturbances, the proposed approach is vulnerable to noisy measurements. However, the response accuracy has been estimated up to +/- 36.7 mm.