Affiliation: | a Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 10, 1113, Sofia, Bulgaria b Central Laboratory of Optical Storage and Processing of Information, Bulgarian Academy of Sciences, P. O. Box 95, Acad. G. Bonchev Str., 1113, Sofia, Bulgaria |
Abstract: | The photoinduced changes in the complex refractive index n=n ? ik of thin films from the Ge–Se–AgI system with constant ratio Ge/Se=1/4 and concentrations of AgI of 0, 5 and 10 mol% are studied by real time measurements of reflectance (R) and transmittance (T) of the films. The phase delay (δ) between the components of the transmitted wave, which is proportional to the birefringence of the film, is measured in real time as well. The changes in the average value of the refractive index (Δn), and in the average value of the absorption index (Δk) in the imaginary part of n as well as the induced optical anisotropy are estimated by solving the inverse optical problem. It is found that involving small quantities of AgI into a Ge–Se matrix increases the sensitivity of the films, but the anisotropic effects are comparatively weakly in them. The maximum values of changes in the average refractive index (Δn=0.025) and in the average absorption index (Δk=?0.03) are obtained in the films, containing 5 and 10 mol% AgI, respectively. Considerable values of the photoinduced anisotropy – birefringence (Δna≈?0.002) and dichroism (ΔD≈0.05, which corresponds to Δka≈0.035) are observed in films without addition of AgI (“pure” Ge–Se film). |