Photoinduced structural changes in antimony polyphosphate based glasses

A photocontraction effect in amorphous films of the binary glass system 0.20 Sb(PO₃)₃]_n–0.80 Sb₂O₃ has been observed after UV irradiation using the 350.7 nm Kr⁺ ion laser line with 5.0 W/cm². Good optical quality films up to 4.0 μm were deposited on silica substrates at room temperature in vacuum by electron beam physical vapor deposition (EB-PVD) and characterized using WDX, XRD, optical absorption, infrared reflectance, profilometry and atomic force microscopy (AFM) techniques. Very stable glasses were prepared by the melt quenching technique and used as evaporation source for the production of films. The photoinduced structural change (PSC) was observed as a variation of about 6% in the film thickness and this effect is accompanied by a photobleaching of the irradiated area with a blue shift of the optical absorption edge. Otherwise this photoinduced change in the film thickness is very sensitive to the variations in the shape and intensity of the laser beam; therefore several possibilities in optical recording arise from these results.