Broadband NIR emission in novel sol–gel Er3+-doped SiO2–Nb2O5 glass ceramic planar waveguides for photonic applications

This paper reports on the sol–gel preparation and structural and optical characterization of new Er3+-doped SiO2–Nb2O5 nanocomposite planar waveguides. Erbium-doped (100-x)SiO2–xNb2O5 waveguides were deposited on silica-on-silicon substrates and Si(1 0 0) by the dip-coating technique. The waveguides exhibited uniform refractive index distribution across the thickness, efficient light injection at 1538 nm, and low losses at 632 and 1538 nm. The band-gap values lied between 4.12 eV and 3.55 eV for W1–W5, respectively, showing an excellent transparency in the visible and near infrared region for the waveguides. Fourier Transform Infrared (FTIR) Spectroscopy analysis evidenced SiO2–Nb2O5 nanocomposite formation with controlled phase separation in the films. The HRTEM and XRD analyses revealed Nb2O5 orthorhombic T-phase nanocrystals dispersed in a silica-based host. Photoluminescence (PL) analysis showed a broad band emission at 1531 nm, assigned to the 4I13/2 → 4I15/2 transition of the Er3+ ions present in the nanocomposite, with a full-width at half medium of 48–68 nm, depending on the niobium content and annealing. Hence, these waveguides are excellent candidates for application in integrated optics, especially in EDWA and WDM devices.

► Novel sol–gel erbium-doped SiO2-based nanocomposites waveguides.
► Rare earth doped Nb2O5 nanoparticles fabricated using a bottom-up approach.
► Unusual broadband NIR emission in glass ceramic system.
► Luminescence properties enables their use not only in the C-band, but also in the S-, and L-bands.
► Potential application as wavelength division multiplexing devices (WDM) and optical amplifiers.