MECHANISM OF RECORDING AND ERASING OF OPTICAL INFORMATION BY LASER-RADIATION ON SIO2-(CO-SIO2-SI MULTILAYER STRUCTURE(SI))

The optical properties of SiO2-(Co + Si)-SiO2-Si structures studied by treatment with Q-switched YAG:Nd and CO2 lasers are presented. The ph oto-thermo-chemical reaction of Co with Si has a threshold character. No change in optical properties of (Co + Si) mixture was observed up t o 2 MW/cm(2) intensities of CO2 laser radiation. A decrease of the ref lection coefficient R (at lambda = 663 nm) from 70% to 45% is observed as the intensity is increased up to 8 MW/cm(2). When this multilayer structure is subject to Q-switched YAG:Nd laser radiation of an intens ity from 14 MW/cm(2) to 53 MW/cm(2), the magnitude of the reflection c oefficient returns to its initial value of 70%. It means that informat ion recorded by the CO2 laser is erased. Calculations of the temperatu re field during irradiation with CO2 and YAG:Nd laser showed that the phase transition from mixture (Co + Si) to CoSi2 caused by CO2 laser i rradiation results in recording of information, whereas the thermal im pact caused by YAG:Nd laser irradiation results in amorphization of Co Si2 and erasing of information. (C) 1997 Elsevier Science B.V.