Inorganic nanoparticles in fiber laser technology

Rare earth doped yttrium aluminium garnet represents a key photonic material for the construction of active optical fibers and scintillators. The successful impregnation of garnet nanoparticles in the fibers is a major technological step that is usually covered by nanoparticle deposition method. We present the correlations between the morphology of the silica frit, nanoparticle size and final concentration of the dopants in the preform. Silica frit exhibited a wide pore size distribution with the smallest pore size of 138 nm and the maximum of 321 nm. Thermal processing of sol-gel precursors followed by controlled sedimentation allowed the preparation of a set of colloidal solutions containing holmium doped yttrium aluminium garnet with tailored nanoparticle sizes. The nanoparticles of the size of 205 nm were successfully impregnated in the frit and processed in the preform showing the refractive index difference of 0.009. The results impact the technology of active optical fibers which can be used for construction of fiber lasers and distributed sensors of harmful radiation.