PHOTOLITHOGRAPHIC METHOD FOR PRODUCING METAL-DISSOLVED DIFFRACTIVE STRUCTURES IN AS-S GLASSES

Gratings are fabricated by the metal-photodissolution effect in evapor ated As33S67 glass, using a novel method which may overcome the disadv antages of previous methods based on holographic or contact mask expos ure. The proposed method involves the generation of the initial metal pattern (Ag or Cu) on a substrate, followed by evaporation of the chal cogenide overlayer. Ag gratings with periods, Lambda, of 12, 10, 8 and 6 mu m and depths, d of 0.35-0.42 mu m have been fabricated in this w ay. This approach offers more flexibility than previous methods, and h as interesting potential for the fabrication of curved-profiled micros tructures (e.g. microlens arrays) by the appropriate exposure or heati ng regime. The stability of the gratings is investigated by monitoring the time-resolved diffraction efficiency during photodissolution of t he metal grating source into the As33S67 overlayer.