Precisely controllable fabrication of Er3+-doped glass ceramic fibers: novel mid-infrared fiber laser materials.

We demonstrated remarkably enhanced 2.7 μm emission in glass-ceramic (GC) fibers containing NaYF₄:Er³⁺ nanocrystals with 980 nm excitation for the first time. The melt-in-tube technique is of scientific and technical significance for the fabrication of GC fibers in comparison to the conventional rod-in-tube technique. The obtained precursor fibers, in which the structure can be maintained well, exhibit no obvious element diffusion or crystallization during the fiber-drawing process. After a careful heat treatment, NaYF₄ nanocrystals were controllably precipitated in the glass fiber core. Owing to the incorporation of Er³⁺ ions into the low phonon energy NaYF₄ nanocrystals, enhanced 2.7 μm emission was achieved from the Er³⁺-doped GC fibers, which was almost undetectable in precursor fibers due to the high phonon energy of the borosilicate glass fiber matrix. Moreover, the 2.7 μm emission lifetime was obtained due to the excellent emission properties of Er³⁺ in the GC fibers. The transmission loss values of precursor fibers and GC fibers at 1310 nm were measured to be 7.44 dB m⁻¹ and 11.81 dB m⁻¹, respectively. In addition, a theoretical simulation based on the rate equations and propagation equations was performed to evaluate the possibility of 2.7 μm laser output. The excellent optical properties endow the GC fibers with potential applications for mid-infrared fiber lasers. [ABSTRACT FROM AUTHOR]