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The dependencies of linear losses coefficient cx, two-photon absorption constant , optical damage threshold I and pseudogap width E0 on structure and concentration changes of glasses from glass-forming region of Ge-As-S system along the As-Ge52, As-Ge2S3, As2S3-Ge52 and As253-Ge253 sections have been experimentally studied. The critical values of concentration and average coordination number at that the cx, 3 and I, reach its extremums were determined. These resultshave been discussed in terms of phase and structure-topological transitions.Keywords: two-photon absorption constant, optical damage threshold, average coordination number, structure-topologicaltransition. 1 .INTRODUCTION The chalcogenide glassy semiconductors are above large interest now due to opportunity of its wide application innon-linear optics and laser technique. The wide glassforming regions of the As-Ge-S system allow to fabricate variety of component composites of the glasses with wide range of optical, physical and chemical properties, that does it useful for different laser elements. Bat therelatively low optical damage threshold of this glasses is the main restriction for its application in power laser devises. Theirwell-known high transmissivity in the infrared region together with the advanced microfabrication techniques available, makethis glasses attractive also for the using in nonlinear optical devices.Recently it was shown that topology plays important role in chalcogenide glass structure, that exhibit medium rangeorder in atomic arrangement"2. However, common direct methods of medium range order studying are absent now. That iswhy the investigations deal with topological features ofthe structure due to different coordination of atoms are required. |
