Planar step-index waveguides obtained via sol-gel synthesis from organometallic precursors

Inorganic and hybrid sols obtained from Si, Ti, Zr and Ce organometallic precursors were used to prepare single and multilayer coatings with different thicknesses. Planar step-index waveguides with different refractive indices were thus prepared by dip-coating the above sols onto commercial soda-lime glass substrates, followed by appropriate thermal annealing. The resultant coatings were characterized by transmission electron microscopy and energy dispersive X-ray spectrometry to elucidate the interface and bonding between the sol-gel derived coatings and the glass substrates. Diffusion of alkali and alkaline earth elements from the glass into the coating layer was confirmed and proposed to play a role in the coating-substrate bonding, inducing excellent optical quality planar interfaces. Optical waveguide characterization performed on a 4.15 μm thick hybrid SiO2:CeO2 (95:5) step-index waveguide yielded losses of 1.50 dB/cm. © 2013 Springer Science+Business Media New York.Work supported under the auspices of MICINN (TEC2006-10469, CEN 2007-2014, SURFALUX SOL-00030930 and MAT2010-18519), DGA (Laser Applications Laboratory T87), and XUNTA DE GALICIA/FEDER (PN2012/019) are acknowledgePeer Reviewe