APPLICATION OF CHALCOGENIDE GLASSES IN INTEGRATED AND DIFFRACTIVE OPTICS

We report on the use of the metal photodissolution effect in chalcogenide glasses to fabricate structures for integrated and diffractive optics. In the case of As-S films photodoped with Ag, the photodoped material was found to be transparent from the near IR to beyond 12-mu-m. Electron microprobe analysis of the composition of the photodoped films revealed that Ag-photodoped As40S60 consists mainly of two As-S-Ag phases whereas Ag-photodoped As30S70 has a single composition corresponding to that of the crystalline compound smithite (AgAsS2). In addition, a Secondary Ion Mass Spectroscopy (SIMS) analysis showed that for Ag-photodoped As30S70 there is a gradual decrease in Ag concentration with depth, indicating that the optical constants may vary slightly through the film. Photodarkening was found to decrease with increasing sulphur content, becoming negligible near As30S70, which may therefore be the optimum composition for these applications. Both surface relief and phase gratings have been fabricated using the photodissolution of Ag in As-S films and diffraction efficiencies of up to 35% at 632.8 nm and 1.5-mu-m have been measured.