Sol−Gel-Processed SiO₂/TiO₂/Poly(vinylpyrrolidone) Composite Materials for Optical Waveguides

Abstract

SiO 2 /TiO 2 /poly(vinylpyrrolidone) (PVP) composite materials processed by the sol-gel technique were studied for optical waveguide applications. Change of refractive index through the range 1.39-1.65 at 633 nm (optical wavelength) was achieved by varying the ratio between the SiO 2 and TiO 2 concentrations. To produce low optical propagation loss in the waveguide, it was necessary to avoid the precipitation of TiO 2 particles caused by the fast hydrolysis reaction of titanium alkoxide. By using titanium ethylhexoxide as a titanium alkoxide together with acetic acid and 2-propanol as the solvent, the precipitation of TiO 2 was avoided in the TiO 2 concentration range of up to 30 wt %, resulting in low optical propagation losses in the slab waveguide configuration. In the higher TiO 2 concentration range, an additional measure, peptization was necessary. With this method, we could produce optical waveguides possessing optical propagation losses of 0.62 dB/cm or lower at 633 nm. Low optical propagation loss in all the TiO 2 concentrations, from 0% TiO 2 /50% SiO 2 /50% PVP to 50% TiO 2 /0% SiO 2 /50% PVP was achieved. The reactions of the sol-gel precursors were also studied using UV-visible and FT-IR spectroscopy.

Nano Fibres by Electro spinning: Properties and Applications

“…Gibson et al 106 Produced electrospun fibres containing pH-adjusting compound for use in wound dressing or protection from contamination. Electrospun fibre mats were produced from PLA, polyethylene co-vinyl acetate (PEVA) and their blend (50,50) and the potential of the mats were also explored as drug delivery vehicles using tetracycline hydrochloride as a model drug. 107 Matthews et al 42 produced scaffolds composed of collagen nano fibres and found that the structural properties varied with the tissue of origin, the isotope and the concentration of the collagen solution.…”

“…In an earlier work titanium tetraisopropoxide was mixed with PVP in 2-propanol from which TiO2/PVP composite films and optical wave guiding structures were fabricated. 50 Kataphinan et al 51 Used organic and inorganic fibres based on glass/ceramic fibres for high temperature applications. Randomly oriented or uniaxially aligned arrays of magnetic nickel ferrite (NiFe 2 O 4 ) nano fibres with an average diameter of 46nm were fabricated by electro spinning.…”

“…At a certain field strength fine continuous jet is ejected beyond that the jet becomes unstable and multiple jets are ejected. Shin et al 50 observed that with the increase in electric field, the polymer jet thins more rapidly and the cone region becomes shorter and more concave in profile. It has been observed that as electric field strength increases, the diameter of nano fibres decreases.…”

Sonochemical-assisted fabrication of biologically active chiral poly(ester-imide)/TiO2 bionanocomposites derived from L-methionine and L-tyrosine amino acids

“…Therefore, it has a widespread range of applications, e.g. in filters, lenses, reflectors, optical adhesives and antireflection films [16][17][18], optical waveguides [19], photochemical solar cells [20], and TiO 2 -based photocatalytic detoxification of air and water for environmental remediation [21][22][23][24]. Owing to the escalating performance characteristics demanded on polymers in various fields, use of poly(ester-imide)s (PEI)s because of favorable properties, such as good heat resistance, mechanical strength, electrical insulation and other physical properties are growing steadily.…”

Luminescence Properties of Anthracene Chromophores in Cyclosiloxane-Based Hybrid Polymer Films

“…They serve as good insulating layers as well as optical transparent waveguides. [7][8][9] Development of organic and inorganic hybrid materials preparation enables us to combine inorganic and organic components at the molecular level. In fact, luminescent chromophores are incorporated in inorganic matrices through sol-gel method.…”