It is well known that light propagation in optical fibers is accompanied by random omnidirectional scattering. This type of scattering is called ‘Rayleigh scattering’ and is due to small inhomogeneities in the fiber core. The small fraction of coherent guided light that escapes outside the cladding of the fiber forms a speckle pattern. While works which make use of the spackles formed by light which is transmitted through the fiber and exits its distal end are abundant, using the light which escapes the fiber laterally has not been implemented in the past.

Recently we have been able to retrieve visual information imaged into the input facet of a multimode fiber with a transparent buffer. This was performed using a Convolutional Neural Network (CNN) which analyzed the side-scattered light from several locations along the fiber. This demonstration can promote the development of distributed optical imaging systems and optical links interfaced via the sides of the fiber.

Applications

• A new generation of medical endoscopes – To date all endoscopes can only gather visual information at the distal end of the fiber. Our suggested technology would allow to gather visual information at the sides of the fiber, greatly increasing the utility of their use.
• A new generation of distributed fiber sensors – There are many applications of fibers as distributed sensors used to gather information on the surrounding of the fiber through coupling of acoustic modes to optical modes. Here, the addition of optical information modality to the distributed optical fiber sensor can increase its functionality as a monitoring device.

Patent:

VISUAL DATA TRANSFER BETWEEN THE END AND SIDE OF A MULTIMODE FIBER, PCT/IB2021/056475