Recent advances in preparation of high-purity chalcogenide glasses for mid-IR photonics

The paper gives the recent achievements on the development of chalcogenide glasses and fibers with various functional properties. The current methods for preparation of high-purity chalcogenide glasses, including the samples doped with rare earth ions, have been reviewed. The novel effective multi-stage techniques for purification of chalcogenide glasses, such as a low-temperature synthesis of glasses via their iodides, the chemical distillation process of initial and intermediate glass components, the method of chemical vapor transport reactions, have been developed and described. The optical transmittance of the produced glasses, their physico-chemical properties and the content of limiting impurities were determined. The best prepared glass samples have low content of limiting impurities (in ppmwt): oxygen - < 0.1, carbon - < 0.5, hydrogen - < 0.02, silicon - < 0.1, transition metals - < 0.05. Using the double crucible technique, the multimode and single-mode fibers were fabricated; their optical and mechanical properties were investigated. Minimum optical losses in multimode As-S, As-Se, Ge-As-Se and As-Se-Te glass fibers were < 100 dB/km in the mid-IR range. Minimum optical losses in core-clad Pr3 +-doped Ge-As-Ga(In)-Se glass fibers were ≤ 1 dB/m. The obtained chalcogenide fibers were tested for photonic applications.