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

Abstract This paper reports on the sol–gel preparation and structural and optical characterization of new Er 3+ -doped SiO 2 –Nb 2 O 5 nanocomposite planar waveguides. Erbium-doped (100- x )SiO 2 – x Nb 2 O 5 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 SiO 2 –Nb 2 O 5 nanocomposite formation with controlled phase separation in the films. The HRTEM and XRD analyses revealed Nb 2 O 5 orthorhombic T-phase nanocrystals dispersed in a silica-based host. Photoluminescence (PL) analysis showed a broad band emission at 1531 nm, assigned to the 4 I 13/2  →  4 I 15/2 transition of the Er 3+ 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.