The University of Southampton

Optical Fibre Sensors and Devices

Our group develops a variety of innovative optical fibre devices and sensors. There are seven central themes:

Nuclear Sensors

We develop fibre scintillators based on pure silica doped with small amount of rare earths to avoid quenching. Scintillating fibres are then connected to photomultipliers by large area conventional fibres. These have been tested with γ-rays, X-rays, β-particles, and neutrons.

Multicore scintillating fibres doped with Li have been used to produce high resolution imaging of thermalised neutrons.

Distributed fibre sensors

Our research efforts currently include the distributed sensing of vibrations, 3D shape, temperature, and magnetic field, using Rayleigh, Brilluoin and Raman scattering.

Our 3D shape sensors use BOTDR analysis to monitor the different strain level at different cores of a multicore fibre and retrieve the fibre curvature and twist.

Distributed Acoustic Sensors (DAS) focus on the extension of the sensing range, frequency range, and strain sensitivity for applications in seismology, O&G, and traffic and perimeter monitoring. We developed a portable unit that can travel internationally for field tests.

In relation to Distributed Temperature Sensing (DTS) we develop new sensing architectures for high speed, high resolution sensing.

Our work on Magnetic Field Sensors aims to develop a speciality fibre for measurement of sub-Gauss magnetic field.

Laser assisted engineering of optical fibres

Focused femtosecond pulses can ionize virtually any material. Transparent media are of particular interest, as the energy of such a pulse is deposited into the material via nonlinear absorption only at the very point of focus. By scanning glass substrate with a laser beam embedded photonic components such as waveguides, couplers, gratings, diffractive optical elements can be inscribed. Our group has developed a range of optical components for integrated optics using this approach.

One of the main directions of our research group is the modification of optical fibres. The high resolution of laser writing allows the selective modification of fibres with complex geometry such as multicore or hollow-core optical fibres. Together with our collaborators from University of the Basque Country we demonstrated optical multicore strain sensors for aerospace applications. The technology has also enabled the development of high-sensitivity optical fibres for OTDR (optical time domain refractometry) and OFDR (optical frequency domain refractometry) systems. The response of our laser modified optical fibres is enhanced a hundredfold while the optical losses remain close to that of a normal optical fibre. Thanks to such fibres, the range of OTDR systems can be significantly expanded. An automated writing system allows us to process kilometers of optical fibre making it into a viable approach for different OTDR applications.

Scattering spectrometer

Optical scattering spectrometers use scattering materials to spatially decompose the spectral components of light. Each wavelength is turned by a scattering medium into a speckle pattern which serves as a unique fingerprint. With a comprehensive base of such light “fingerprints”, an unknown spectrum of light can be analysed. The integration of the various fibrerised and bulk components allows for the manufactured of an extremely compact, minimal weight spectrometer. The scattering spectrometer can be used for spectral analysis of materials, metrology, measurement of optical sensors.