Kinetics of optically induced reaction between silver and As30S70 films was measured by monitoring the change in thickness of the undoped chalcogenide using a modified computer-controlled reflectivity technique. Silver concentration profiles during optically induced solid state reaction (OSSR) were traced by means of Rutherford backscattering spectroscopy (RBS). The composition of the As-S films was chosen to be As30S70, which is the most favorable for optically induced solid state reaction, because it yields a homogeneous photodoped product. A new technique of step-by-step optically induced solid state reaction of Ag into As30S70, amorphous films, which has allowed to design films with exact silver concentration and to study their properties, is reported. The host As30S70 films were photodoped by consecutively dissolving a thin (similar to 20 nm) layer of silver, which resulted in homogeneous films of good optical quality. The silver concentration of the films ranged between 1 and 27 at.%. We have analyzed in detail the influence of the silver doping in the host material on optical and thermal properties, and its structure. The photodoped films produced a single-phase homogeneous material with its structure close to AgAsS2 in some of them. Results of all analytical techniques have helped to understand the processes taking place during silver photodissolution.