Impact of Raman scattering and modulation instability on the performances of Brillouin sensors

The impact of Raman scattering and modulation instability is studied in Brillouin time-domain analysis systems. It turns out to be very detrimental for long-range sensing as a result of the extended interaction length combined to the high pump peak pulse power. The conditions under which these effects limit the sensing range are determined and the modeling is very well confirmed by experimental results

High Spatial and Spectral Resolution Long-Range Sensing Using Brillouin Echoes

While classical configurations have a practical spatial resolution of 1 meter, novel approaches have been demonstrated that can overcome this limit to offer spatial resolutions in the centimetre range, while preserving full measurand accuracy

Fast measurement of local PMD with high spatial resolution using stimulated Brillouin scattering

Abstract Local beat length with a 21.5cm spatial resolution is measured in one second along a single mode fibre using the polarisation dependence of stimulated Brillouin scattering, in a non-destructive and simple way. Introduction It has been demonstrated over the past two decades that polarisation mode dispersion (PMD) may limit the ultimate data rate through an optical fibre. The basic reason for PMD is the presence of intrinsic or induced birefringence within the fibre. Measuring the local birefringence would thus provide key information to localize the fibre segments mainly contributing to PMD, so that an efficient action could be undertaken for cable upgrade. A simple solution based on Rayleigh reflectometry using polarized light, the socalled POTDR techniqu

High performance Brillouin distributed fibre sensor

We propose a novel configuration for a Brillouin distributed sensor based on Brillouin optical time domain analysis. This new configuration eliminates many intensity noise issues found in previous schemes. Resolution of 3.5 m all over a 47km single-mode fibre was achieved and resolution down to 30 cm in a few kilometre fibre. Noise reduction makes possible measurements with a 16 times averaging

High spatial and spectral resolution long-range sensing using Brillouin echoes

High spatial (~cm) and spectral (~MHz) resolution Brillouin sensing is realized with enhanced signal to noise ratio using a pre-activated acoustic field and an optical phase control over the interrogating pulse. Pre-activation of the acoustic field preserves the Brillouin natural linewidth and a differential gain technique extends the method to long ranges. Experimentally, fully resolved measurements of the Brillouin frequency shift of a 5 cm spot perturbation at the far end of a 5 km fibre have been performed with a frequency resolution of 3 MHz ( 2 sigma ), using a 500 ps (5 cm) pi phase shift pulse

Complete experimental characterization of stimulated Brillouin scattering in photonic crystal fiber

International audienceWe provide a complete experimental characterization of stimulated Brillouin scattering in a 160 m long solid-core photonic crystal fiber, including threshold and spectrum measurements as well as positionresolved mapping of the Brillouin frequency shift. In particular, a three-fold increase of the Brillouin threshold power is observed, in excellent agree-ment with the spectrally-broadened Brillouin gain spectrum. Distributed measurements additionally reveal that the rise of the Brillouin threshold results from the broadband nature of the gain spectrum all along the fiber and is strongly influenced by strain. Our experiments confirm that these unique fibers can be exploited for the passive control or the suppression of Brillouin scattering

The Making of a Good Brillouin Distributed Fiber Sensor

By analyzing the fundamentals of the operation of Brillouin sensors it will be shown that all efforts must be focused on obtaining the largest signal-to-noise ratio on the raw optical signal, which ultimately scales all performance of the sensor. Guidelines will be presented, together with recent research efforts to find out smart solutions pushing further the limits