Thermal stability and photoluminescence properties of RE-doped (RE = Ho, Er, Tm) alumina nanoparticles in bulk and fiber-optic silica glass

Nanocrystalline ceramic coatings for the capillary fiber lasers

“…The value of the radiative lifetime was 7.30 ms and the related R-square was 0.9976 confirming the applied single-exponential approximation. This value is significantly higher than a value of 1.35 ms reported for Ho 3+ -doped silica fiber containing alumina nanoparticles [11]. This superior increase of the radiative lifetime validates the application of nanocrystalline films and particles to improve the overall fiber laser properties.…”

“…Controlled crystallization of inorganic luminescent nanocrystals inside a fiber core is a common way to improve the fiber laser efficiency [7][8][9][10]. The nanocrystals usually support the radiative transition of incorporated rare earth element allowing to improve their overall luminescence properties [11]. Application of the active films into the capillary or microstructure fibers represents a promising alternative to conventional optical fibers.…”

Luminescence lifetime of Er-doped silica optical fibers: the role of composition and fabrication processing

“…In both optical fibers, the Er 3+ ions are homogenously distributed in a single environment with lifetime ≈9.2 μs. This value is typical for alumino-silicate glass and can be ascribed to Er 3+ ions homogenously distributed in the alumino-silicate network 10,18 . The preform and cane samples exhibit the same lifetime component, but a second, fast component is observed as well, which corresponds to a different Er 3+ environment.…”

“…Another possibility is the incorporation of Er 3+ ions in a crystalline phase, likely mullite 3Al2O3.2SiO. It was previously shown that the moderate cooling rate during the preform collapse is favorable to the crystallization of mullite 10,20 , and that Er 3+ ions embedded in mullite nanocrystals exhibit faster lifetime (τ < 5 ms) than in amorphous alumino-silicate glass 10 . The results warrant further investigation.…”

“…The optical fiber preform is made by vapor deposition of a porous SiO2 layer inside a silica tube, which is subsequently soaked by a dispersion of Al2O3 nanoparticles and RE chlorides. The porous tube is then sintered into a preform and drawn into fiber at temperatures above 1900 °C, which leads to the dissolution of the nanoparticles and formation of an alumino-silicate core 10 . Various other processing stages, such as preform elongation, may be employed in the making of specialty optical fibers, such as nanostructured-core fibers 11 .…”