Optical fiber based sensor system for monitoring of infrastructures

Febus Optics is an innovative company based in Pau (France) bringing a new generation of optical fiber based sensor system to the market, in particular for the maintenance and monitoring of infrastructures.

Technical details

Brillouin scattering process

Brillouin scattering process


The light backscattered by an optical fiber segment without any defects or abnormal characteristics is spectrally decomposed into three distinct peaks corresponding to three outstanding phenomena:

Rayleigh scattering: The electromagnetic wave propagating in the fiber core interacts with the scattering centers, silica impurities and enhancing additives.
Raman Scattering: The Raman effect is an interaction between light and thermal vibration of silica molecules. As such, this phenomenon is highly dependent on temperature at the spectral level.
Brillouin Scatteing: The Brillouin effect originates from photon-acoustic phonon interaction. It generates light with a Frequency shift of approximately 10th GHz compared to the incident light.

The Brillouin Frequency Shift is called Brillouin Frequency. It is sensitive to both temperatur and strain allowing FEBUS-G1 to measure both parameters.

Distributed Sensing

Distributed Sensing

As light is propagating in optical fiber at a given velocity, it is possible to locate precisely from where backscattered light takes origin. Thus on the detector, at one time, corresponds one backscattering position.

It is a common technique utilized by telecom operators called OTDR (Optical Time-Domain Reflectometer) It was initially created to analyze losses inside optical telecommunication lines. It only measures variation on signal intensity.

FEBUS-G1 performs a full Brillouin Frequency measurement of the signal at each point. That is why it can be categorized as B-OTDR (Brillouin Optical Time-Domain Reflectometer).