The purpose of this project is to explore the potential of new preparation processes of magneto optical (MO) materials for applications in guided optics. The project is based on unique know how to IPCMS: to the development of materials initiated by the Département de Chimie des Matériaux Inorganiques of the IPCMS and developed by the RBNano company, functionalisation of integrated optical waveguides and ultrafast magneto-optic processes in Département d’Optique ultrarapide et de Nanophotonique, also part of IPCMS.
Today, the MO sensors market is mainly dominated by electronic based devices. Among the most sensitive ones, the SQUID (Superconducting QUantum Interference Device) is prevailing for very low field measurements. It finds notably applications for magneto-encephalography where a few hundreds of these sensors operate in parallel. The sensitivity of SQUIDs is around some fT.Hz-1/2, but requires a cooling at 4 K to reach these performances.
We propose to change the paradigm of high resolution magnetic sensing moving from electronic based devices to optical devices.
The optical measurement of the magnetic field relies on the Faraday effect, modifying the polarisation of the light with the amplitude of a magnetic field and depending on the material properties and the interaction length. The light can be brought to the material and collected back using an optical fiber with some advantages: Made of silica, the fibers do not interact with the electromagnetic environment. As the light is fully confined, the signal does not experiment any cross-talk, even for dense fiber bundle. The optical fiber can transport the optical signal over large distance without attenuation and their diameters are typically around 100 μm. This allows remote detection and parallel operations. Finally, the MO sensors can operate at room temperature.
We plan implement micrometric MO element directly at the end of the optical fiber, reducing the sensor size to the diameter of the fiber. The literature shows that a noise equivalent sensitivity of 20 fT is already achievable. Operating at room temperature, no cooling system is required. It will be possible to bond the source of the magnetic field and the sensor to increase the signal intensity and the spatial resolution.
The heart of the project is the development of two types MO materials combining very high efficiency and ease of processability for the implementation on the optical fiber.