Thermal optical properties of TiO2 films

A fibre optic experimental arrangement was used to determine the thermo-optic coefficient (dn/dT) of electron beam deposited titanium dioxide coatings on the cleaved end faces of multimode optical fibres for a wavelength range between 600 and 1050 nm. The temperature-induced change in the index of refraction (n) and extinction coefficient (k) were successfully determined from reflection spectra. Measurements of n and k at various wavelengths for different temperatures enabled the determination of dn/dT and dk/dT. It was found that dn/dT takes different values at different temperature ranges. For example, at 800 nm, dn/dT was (-1.77 +/- 0.7) x 10(-4) K-1, between 18degreesC and 120degreesC, and took a value of (-3.04 +/- 0.7) x 10(-4) K-1 between 220degreesC and 325degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.