Abstract-A novel configuration for a Brillouin distributed fiber sensor based on Brillouin optical time-domain analysis is proposed. This configuration eliminates many intensity noise issues found in previous schemes. Resolution of 7 m all over a 47 km single-mode fiber was achieved and resolution down to 30 cm in a few kilometer fiber. Noise reduction makes possible measurements with a 16 times averaging.Index Terms-Brillouin scattering, nonlinear optics, optical fiber sensors.

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This work is meant to provide a review of different multiplexing topologies employing distributed erbium-doped fiber and Raman amplification to solve the problem of powerloss compensation in fiber-optic sensor (FOS) networks. This is a key parameter in large multiplexing networks, particularly when employing intensity-modulated sensors. These topologies are studied both theoretically and experimentally, and a comparative analysis is carried out between them. The main parameters considered in the analysis are power budget, optical signal-tonoise ratios, scalability and architecture complexity.Comparison of the measured optical spectrum of amplified single and double bus networks for sensor multiplexing.

In this work, we demonstrate a stable fiber sensing system for remote temperature measurements, where the sensing element is an array of four fiber Bragg gratings (FBGs) and sensor interrogation is achieved with a multi-wavelength erbium fiber ring laser. By introducing a feedback fiber loop in a fiber ring cavity, four laser emission lines were obtained simultaneously in single-longitudinal mode operation (SLM). The power instability obtained was lower than 0.5 dB with an optical signal-to-noise ratio (OSNR) higher than 50 dB for all the emitted wavelengths. The application of this system for remote temperature measurements has been demonstrated even though the SLM regime cannot be preserved.