Optical properties of SiO2–TiO2 thin film waveguides obtained by the sol–gel method and their applications for sensing purposes

Rare-earth photoluminescence in sol–gel derived confined glass structures

“…The sol-gel method, based on wet chemistry processing, is quite cheap and simple for the fabrication of multicomponent planar waveguides, where significant RE ion concentrations, in particular Er 3+ , can be achieved [5]. Among different binary systems, SiO 2 -TiO 2 has been extensively employed as a host material for Er 3+ ions [5][6][7][8][9][10][11], mainly because it offers the possibility of producing planar waveguides with a significant refractive index contrast, depending on the TiO 2 /SiO 2 ratio. Other methods which can be used to prepare such waveguides include the use of Er-doped ormosils prepared by organic/inorganic sol-gel processing [12], or the use of fabrication techniques such as ion-exchange and sputtering [13], or flame hydrolysis deposition [14].…”

Experimental study of perfectly patterned silica-titania optical waveguide

“…The high index contrast between the silica substrate and the film layer can be maintained by the use of the silica-titania mixed system. By varying the silica and titania alkoxide concentrations in the mixed sol greater tunability of index contrast can be obtained [8]. The thicknesses of the silica-titania films are measured precisely after subsequent heat treatment.…”

“…It is capable of coating large surfaces and does not require high processing temperatures. Lukowiak et al [8] showed a silica-titania waveguide with a grating coupler, but they used a polymer photoresist on which the grating structure was inscripted by holographic exposure. This is a cumbersome affair whereas the soft lithographic technique is much easier to process.…”

Nanostructured Er3+-doped SiO2–TiO2 and SiO2–TiO2–Al2O3 sol–gel thin films for integrated optics

“…The binary silica-based systems, such as silica-titania [1][2][3], silica-hafnia [3], silica-alumina [4], silica-alumina [5], silica-zirconia [6] and phosphosilicate [7] are of particular interest allowing the tailoring of the optical and spectroscopic properties. Nonlinear effects have been also observed in silica-titania waveguides, i.e.…”

“…On the one hand, these processes are detrimental to the efficiency of optical amplification and lasing at 1.5 lm, but on the other hand, they open applications as energy up converters [15], as well as diode pumped visible and ultraviolet laser devices [1,16]. Zampedri and coworkers [17] prepared in the SiO 2 -TiO 2 binary system planar wave guides activated with 1% molar Er 3+ , considering that for obtaining good optical and spectroscopic properties, the TiO 2 content should be in the molar ratio of 7-12%.…”