Preparation of low-loss core–clad As–Se glass fibers

• Methods for producing high-purity arsenic selenide glasses have been developed.
• Arsenic selenide glasses with the ultra-low content of residual impurities are prepared.
• Optical fibers of high-purity As30Se70–As40Se60 glass compositions are drawn.
• The minimum optical loss in core–clad As–Se fiber was 67 dB/km in the 6–6.5 μm spectral range.

Arsenic selenide glass with the low content of residual impurities (hydrogen ⩽0.02 ppm wt, oxygen <0.1 ppm wt, carbon <0.5 ppm wt, silicon ⩽0.1 ppm wt, and metals 0.01–0.1 ppm wt) is prepared. The effect of the method for producing arsenic selenide on the content of limited impurities and the optical transmission in the mid-IR range is investigated. Optical fibers of high-purity As30Se70–As40Se60 glass compositions are drawn. The minimum optical loss in unclad As35Se65 glass fiber of diameter 200 μm is 70 dB/km at wavelengths of 2.7 and 3.8 μm. The minimum optical loss in core–clad As40Se60/As38Se62 glass fiber is 67 dB/km in the 6–6.5 μm spectral range, which is the best result for the core–clad As–Se glass fibers.