6533b823fe1ef96bd127fdb2

RESEARCH PRODUCT

Local structure aroundEr3+inSiO2−HfO2glassy waveguides using EXAFS

subject

description

${\mathrm{Er}}^{3+}$-doped $\mathrm{Si}{\mathrm{O}}_{2}\text{\ensuremath{-}}\mathrm{Hf}{\mathrm{O}}_{2}$ glassy waveguides with $\mathrm{Hf}{\mathrm{O}}_{2}$ concentrations ranging from $10\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}50\phantom{\rule{0.3em}{0ex}}\mathrm{mol}\phantom{\rule{0.2em}{0ex}}%$ were prepared using the sol-gel route and deposited on $v\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{2}$ substrates using the dip-coating technique. The local environment around ${\mathrm{Er}}^{3+}$ ions was determined from Er ${L}_{3}$-edge extended x-ray-absorption fine-structure (EXAFS) measurements. The first coordination shell around ${\mathrm{Er}}^{3+}$ ions is composed of oxygen atoms. Hafnium is the main constituent of the second coordination shell of ${\mathrm{Er}}^{3+}$, differing from the cases of pure $\mathrm{Si}{\mathrm{O}}_{2}$ and $\mathrm{Si}{\mathrm{O}}_{2}\text{\ensuremath{-}}\mathrm{Ti}{\mathrm{O}}_{2}$ glassy hosts, in which silicon is the main atomic species. The local structure around ${\mathrm{Er}}^{3+}$ ions has been found to be independent on $\mathrm{Hf}{\mathrm{O}}_{2}$ concentration within the studied composition range. This fact implies that ${\mathrm{Er}}^{3+}$ ions are preferentially dispersed in $\mathrm{Hf}{\mathrm{O}}_{2}$-rich regions of the glassy waveguide, even at the lowest $\mathrm{Hf}{\mathrm{O}}_{2}$ concentration. For all samples, no ${\mathrm{Er}}^{3+}\text{\ensuremath{-}}{\mathrm{Er}}^{3+}$ coordination shell has been detected by EXAFS. The presented structural results allow us to understand some spectroscopic properties typical of ${\mathrm{Er}}^{3+}$-doped $\mathrm{Si}{\mathrm{O}}_{2}$ glassy waveguides co-doped with $\mathrm{Hf}{\mathrm{O}}_{2}$.