I. V. Skripachev

Single-mode As-S glass fibers

Single-mode As–S glass fibers with a core diameter from 3 to 20 μm and a clad diameter of 125 μm are prepared by the double-crucible method. The cutoff wavelength of the fibers is 0.9–6 μm. The lowest transmission losses in the fibers at 2.2–2.3 μm are ∼100 dB/km, and their mean bending strength is 800–1000 MPa.

Stability of the Optical and Mechanical Properties of Chalcogenide Fibers

The variations in the optical losses and bending strength of high-purity As–S, As–Se, As–S–Se, and As–Se–Te glass fibers during storage in air were studied. The optical properties and strength of fibers with reflecting clads and well-protected surfaces were shown to be sufficiently stable for practical applications. The optical and mechanical properties of uncoated fibers degrade during storage because of adverse surface processes.

Flow of Molten Arsenic Selenide in a Cylindrical Channel

The flow rate of molten arsenic selenide in cylindrical channels is measured at channel diameters of 3.0 to 5.5 mm, channel lengths of 40 to 120 mm, temperatures of 285–320 and 375–470°C, and inert gas gage pressures of up to 1.5 × 105 Pa. It is found that there is a motionless melt layer on the inner surface of the channel. For a channel 4.6 mm in diameter, its thickness is 0.7 mm at 290°C and 0.1 mm at 420°C. In the temperature range 280–315°C, there is a threshold gas pressure below which the melt does not flow. Partial crystallization may occur in the flowing melt. Its effect on the melt flow rate grows as the holding time at 270–320°C increases. The data obtained can be used to choose conditions for producing As2Se3 optical fibers by the crucible method.

High-Purity As2S1.5Se1.5 Glass Optical Fibers

Core–clad optical fibers were fabricated from high-purity As2S1.5Se1.5 glass, and their properties were studied. The arsenic sulfo-selenide was prepared by melting a mixture of high-purity arsenic monosulfide, arsenic, and selenium. Optical fibers with core/clad diameters of 300/400 and 200/400 μm were fabricated by the double-crucible method. The minimum loss was found to be 60 ± 20 dB/km at 4.8 μm and 200–300 dB/km between 4 and 6 μm. The numerical aperture of the fibers was 0.28. A 1.5-m-long section of the fiber transmitted 6-W CO laser radiation. The average bending strength of the 400-μm-diameter fibers was 0.8 GPa.

Low-loss infrared arsenic-chalcogenide glass optical fibers

This paper reports recent achievements in the field of infrared optical fibers based on vitreous arsenic chalcogenides (As2S3, As2Se3, As2Se1.5Te1.5). The minimum optical losses of the fibers from arsenic sulfide, arsenic selenide and arsenic telluride are equal to 20 - 30 dB/km at 2.2 and 3.3 micrometers , 80 - 100 dB/km at 4.3 micrometers , and 100 - 300 dB/km and 6.7 micrometers , respectively. Among them the double polymer coated two-layer arsenic-sulfide optical fibers have the lowest optical losses (20 - 25 dB/km) and the highest mechanical bending strength (1 - 1.5 GPa).

Molecular composition of organic impurities in extrapure sulfur

We have determined the molecular composition of organic impurities in extrapure sulfur obtained by the distillation purification of sulfur recovered from gaseous hydrocarbons. Using vacuum extraction, we obtained a concentrate of impurities highly volatile compared to the major component. Gas chromatography/ mass spectrometry analysis indicated the presence of impurities in the form of hydrocarbons with up to eight carbon atoms and their thio, oxy, and nitro derivatives. The detection of this group of impurities accounts for the distinctive features of the preparation of sulfur with low carbon and oxygen contents through ultrapurification of gas-derived sulfur.