Photolithographic method for producing metal-dissolved diffractive structures in As-S glasses

Gratings are fabricated by the metal-photodissolution effect in evaporated As/sub 33/S/sub 67/ glass, using a novel method which may overcome the disadvantages of previous methods based on holographic or contact mask exposure. The proposed method involves the generation of the initial metal pattern (Ag or Cu) on a substrate, followed by evaporation of the chalcogenide overlayer. Ag gratings with periods, /spl Lambda/, of 12, 10, 8 and 6 /spl mu/m and depths, d, of 0.35-0.42 /spl mu/m have been fabricated in this way. This approach offers more flexibility than previous methods, and has interesting potential for the fabrication of curved-profiled microstructures (e.g. microlens arrays) by the appropriate exposure or heating regime. The stability of the gratings is investigated by monitoring the time-resolved diffraction efficiency during photodissolution of the metal grating source into the As/sub 33/S/sub 67/ overlayer.