Use of thulium-doped LaF3 nanoparticles to lower the phonon energy of the thulium's environment in silica-based optical fibres

New lasers and amplifiers based on rare-earth (RE)-doped silica optical fibres need improved spectroscopic performance. In this context, a route of interest consists of embedding RE ions within nanoparticles of composition and structure different from those of silica. In this report, optical fibres were prepared by doping the preform with LaF3:Tm3+ nanoparticles. Particles react through the process (Modified Chemical Vapor Deposition) to form fluoride-free amorphous nanoparticles that encapsulate the thulium ions. Nanoparticle doping permits enhanced 3H4 lifetimes up to 58 μs with good optical transparency and only 3000 at. ppm lanthanum. We also report on the advantage of doping with nanoparticles in order to control energy transfer.