Optical Communications Group has a broad experience on fiber-optic sensors. From 1992 we have developed fiber sensors and sensors networks. Nowadays we develop both single-point and distributed sensors using our own fabrication technology. We also develop new multiplexing networks for our sensors or commercial ones using optical amplification when needed.

This research field has five main topics:

Distributed Brillouin sensors

Fiber-optic sensors based on the stimulated Brillouin scattering effect can become a truly disruptive technology in the field of structural health monitoring. These sensors can be embedded within materials and structures and provide a fiber-optic “nerve system” that feels the “pain” that they are suffering in the form of strain, stress, deformation, delamination, cracks, temperature variations, and others. Moreover, this type of sensor can be deployed in other monitoring applications such as in power lines, bridges, pipelines, fire detection, process control, etc. For instance, Brillouin distributed sensors (BDS) can be used in electric power lines to measure temperature, which gives an indirect assessment of local current load and degradation of the line. Temperature change detection can also give an indication of leakage in oil or gas pipelines. The main asset of BDS in all these applications is their ability to perform distributed measurements.

Conventional fiber-optic point sensors such as fiber Bragg gratings (FBG) or interferometric sensors just measure at specific locations within a structure, whereas BDS provide a quasi-continuous measurement of strain and temperature along an optical fiber. The sampling interval of this measurement can be made arbitrarily small and, for each sample, the BDSreduction gives an average value of the measurands integrated over the spatial resolution of the sensor. Therefore, a single BDS can replace many point sensors. This translates to an important reduction in costs when monitoring large structures. Further reduction in costs comes from the fact that in BDS a standard single-mode fiber (SSMF) without any modifications is deployed as transducer, in contrast to point fiber optic sensors that require an elaborate manufacturing process.

Research on BDS within the group is focused in the following areas:

• Reduction of the measurement time
• Enlargement of the sensor range
• Enhancement of the sensor spatial resolution
• Simplification and cost reduction of the experimental setup

Contact: Alayn Loayssa, Mikel Sagues