Er3+ / Yb3+ co-doped multi-functional silica phosphate glass films for integrated photonic applications

The multi-component silicate glasses co-doped with Er 3+ /Yb 3+ were fabricated as thin films by the spin coating technique, which was analyzed for their optoelectronic response. Their monolith counterparts synthesized by the sol -gel route were used for the electrical studies. The films evidenced nanocristobalite phases at low levels of doping. The film micrographs explicated gas-trapped circular dimensions on the surface, due to the spreading of the sol on the substrate during the spin coating process. The glasses show a decrease in the number of polarizable non-bridging oxygen units with doping, reducing the polarizability and optical basicity. The films exhibit prominent green lasing in the downshifting process. The energy transfer from the Yb 3+ ions endows the glasses with significant red lasing, suppressing the green emissions by the upconversion mechanism, which is also validated by the colorimetric chromaticity analysis. The gain cross-section of the glass doped with 1.5 mol% of Yb 3+ is 23.3 x 10 -20 cm 2 in the S -band telecommunication domain. The glass film evidences its potential for NIR lasers, beyond a population inversion of 40 %, and a decreasing metastable lifetime of 6.6 mu s. Beyond 1.5 mol% of the co-dopant Yb 3+ , energy transfer dominates, due to the dipole-quadrupole interactions, which has been corroborated by the Inokuti-Hirayama model. The conductivity in the glasses shows a decreasing trend with doping. The Randle ' s equivalent circuitry of the Nyquist impedance plots, predicts Warburg diffusion impedance that deters the space charge polarization. The consequential decrease in the dielectric constant and capacitance makes the glasses suggestive of multi-layer dielectric substrates in the integrated microelectronic technology for soldering of the printed circuit boards (PCB) that demand low signal losses.