In this paper we propose the use of optimized bi-directional distributed Raman amplification to enhance the operating range of Brillouin optical time-domain analysis (BOTDA) sensors. In particular by combining high-power fiber-Raman lasers and polarization-multiplexed Fabry-Pérot lasers operating at 1450 nm with low relative-intensity-noise (RIN), we demonstrate distributed sensing (using first...

The experimental validation of a numerical technique for temperature/strain profile reconstruction based on Brillouin optical-fibre time-domain analysis (BOTDA) sensors is presented. In this approach, we search directly for the Brillouin frequency shift profile along the fibre that matches the measured data. The algorithm is based on a harmonic expansion of the unknown profile, whose coefficien...

We present a new technique for simultaneous measurement of chromatic dispersion and Brillouin shift distribution along conventional, single-mode optical fibers used in telecommunications. It is based on performing Brillouin Optical Time Domain Analysis (BOTDA) over the four-wave mixing generated by two low-power pumps (<10 mW). Unlike others, this technique can measure any arbitrary value ofdis...

Differential pulse-width-pair BOTDA technique is combined with bi-directional Raman amplification and Simplex coding to achieve sub-meter spatial resolution over very long sensing distances. Numerical simulations are used to optimize the power levels of the Raman pumps, avoiding nonlinear effects and pump depletion. Distortions in the Brillouin gain spectrum due to acoustic-wave pre-excitation ...

A theoretical and experimental analysis of the impact of pulse modulation format on Brillouin optical time-domain analysis (BOTDA) sensors using pulse coding techniques has been carried out. Pulse coding with conventional non-return-to-zero (NRZ) modulation format is shown to induce significant distortions in the measured Brillouin gain spectrum (BGS), especially in proximity of abrupt changes ...