Laser-assisted rapid prototyping of silica optical fibers functionalized with nanodiamonds and multiple active rare earth dopants

We present a rapid prototyping method for functionalized silica optical fibers, leveraging laser-assisted preform manufacturing combined with powder-in-tube and sol-gel dip-coating techniques. Laser vitrification enables precise thermal control through an ultra-thin heat blade characterized by localized heating and steep temperature gradients, facilitating high-quality glass formation and the integration of heat-sensitive dopants. We demonstrate three key outcomes: (i) fabrication of Ytterbium-doped active fibers with performance comparable to commercial benchmarks, (ii) development of fibers with fluorescence bandwidths exceeding one octave, doped with multiple rare-earth ions, promising for wide-band telecommunications and ultrashort pulse amplification, and (iii) the first direct doping of silica fibers with nitrogen-vacancy fluorescent nanodiamonds, enabling single-photon quantum emitter integration with the backbone of current information technology networks. Additionally, nanodiamond doping is proposed as a pathway to control the nonlinear refractive index of silica fibers. These findings establish laser-assisted preform fabrication as a versatile and efficient technique for creating advanced optical fibers with innovative functionalities.