On the Enlargement of the Emission Spectra from the I-4(13/2) Level of Er3+ in Silica-Based Optical Fibers through Lanthanum or Magnesium Co-Doping

Improving optical fiber amplifiers requires the elaboration and use of new materials and new compositions. In this sense, we prepared erbium-doped optical fiber samples that were co-doped with magnesium or lanthanum by gradual-time solution doping. Doping concentrations and thermal processes induce the formation of nanoparticles. The effect of lanthanum and magnesium contents on the width of the spontaneous emission of the <mml:semantics> 4 </mml:semantics> I <mml:semantics> 13 / 2 </mml:semantics> level of Er <mml:semantics> 3 + </mml:semantics> was characterized in the nanoparticle-rich fiber samples. For that purpose, the width was characterized by the effective linewidth and the full-width at half-maximum (FWHM). The results indicate the robustness of the effective linewidth to strong variations in the intensity profiles of the <mml:semantics> 4 </mml:semantics> I <mml:semantics> 13 / 2 </mml:semantics> spontaneous emission. Increasing the doping concentrations of both magnesium and lanthanum increases the FWHM and the effective linewidth, along with optical losses. Results show that the fabrication of nanoparticle-rich optical fibers through lanthanum or magnesium doping induces an FHWM broadening of 54% and 64%, respectively, or an effective linewidth broadening of 59% (for both elements) while maintaining a transparency that is compatible with fiber laser and amplifier applications.