AUTHOR=De Oliveira Lima Karmel , Caixeta Fábio José , Souza Vítor Dos Santos De , Rosa Leonardo Sousa , Soares Victor Del Vecchio , Crumo Carolina Assunção , Borin Ivana Aparecida , Ferrari Jefferson Luis , Gonçalves Rogéria Rocha 

TITLE=Super Broadband at Telecom Wavelengths From RE3+-Doped SiO2-Ta2O5 Glass Ceramics Planar Waveguides

JOURNAL=Frontiers in Chemistry

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.915335

DOI=10.3389/fchem.2022.915335

ISSN=2296-2646

ABSTRACT=<p>This paper reports on the preparation of Er<sup>3+</sup>/Yb<sup>3+</sup>/Tm<sup>3+</sup>, Er<sup>3+</sup>/Yb<sup>3+</sup>/Nd<sup>3+</sup>, and Er<sup>3+</sup>/Tm<sup>3+</sup>/Nd<sup>3+</sup> triply doped and Er<sup>3+</sup>-doped SiO<sub>2</sub>-Ta<sub>2</sub>O<sub>5</sub> glass ceramic nanocomposites and active planar waveguides by the sol–gel process using the dip-coating technique as deposition method. The investigation of their structural, morphological, and luminescent properties using XRD, AFM, and photoluminescence analysis, are reported here. The XRD results showed the presence of L-Ta<sub>2</sub>O<sub>5</sub> nanocrystals dispersed in the SiO<sub>2</sub>-based amorphous host for all the nanocomposites and films. The rare earth ion (RE<sup>3+</sup>) doping concentration affected both the crystallinity, and the crystallite sizes of the Ta<sub>2</sub>O<sub>5</sub> dispersed into SiO<sub>2</sub>-Ta<sub>2</sub>O<sub>5</sub> nanocomposites and waveguides. AFM characterization revealed crack free and smooth surface roughness and differences in viscoelasticity on the Er<sup>3+</sup>-doped SiO<sub>2</sub>-Ta<sub>2</sub>O<sub>5</sub> films surface, which allows the identification of Ta<sub>2</sub>O<sub>5</sub> nanocrystals on the SiO<sub>2</sub> amorphous host. The Er<sup>3+</sup> doped and triply doped SiO<sub>2</sub>-Ta<sub>2</sub>O<sub>5</sub> nanocomposites displayed broad- and super broadband NIR emissions with a FWHM up to 173 nm achieved in the telecom wavelengths. The lifetime of the <sup>4</sup>I<sub>13/2</sub> emitting level of the Er<sup>3+</sup>-doped SiO<sub>2</sub>-Ta<sub>2</sub>O<sub>5</sub> waveguides is strongly dependent on Er<sup>3+</sup> concentration and an emission quenching was negligible up to 0.81 mol%. The structural and luminescent investigations indicated that RE<sup>3+</sup>-doped SiO<sub>2</sub>-Ta<sub>2</sub>O<sub>5</sub> glass ceramics are promising candidates for photonic applications in optical devices operating in wide wavelengths at the telecom bands.</p>