Fiber‐draw‐induced elongation and break‐up of particles inside the core of a silica‐based optical fiber

Particles in the core of optical fibers are widely studied to tailor or to improve optical properties. The analysis of nanoparticles embedded in silica‐based optical fiber allowed new observations of the evolution of amorphous particles during fiber drawing. Even at the nanoscale, competition between viscous stresses and surface tension on the particles induces elongation and even break‐up of particles during the process. Indeed, particles between 140 and 200 nm diameter inside the preform can break up in fragments with diameters down to 60 nm inside the drawn fiber. Break‐up of particles appears as a new “top‐down” strategy to produce small particles. These observations are promising for micro/nanostructured and multiphasic optical fibers.