0020-1685/02/3802- $27.00 © 2002 MAIK “Nauka /Interperiodica” 0193 Inorganic Materials, Vol. 38, No. 2, 2002, pp. 193–197. Translated from Neorganicheskie Materialy, Vol. 38, No. 2, 2002, pp. 247–252. Original Russian Text Copyright © 2002 by Churbanov, Shiryaev, Skripachev, Snopatin, Pimenov, Smetanin, Shaposhnikov, Fadin, Pyrkov, Plotnichenko. INTRODUCTION The fabrication and properties of As 2 S 3 and As 2 Se 3 glass fibers have recently been the subject of many studies. At the same time, the information about sulfo- selenide glass fibers is limited. Nishii et al. [1] reported on the fabrication of core–clad optical fibers with the core made from As 40 S 58 Se 2 glass, and the clad made from As 40 S 60 . Sanghera and Aggarwal [2] prepared fibers with an As 40 S 55 Se 5 core and reflecting poly- meric clad. In a previous report [3], we described opti- cal fibers with an As 40 S 30 Se 30 core and As 40 S 35 Se 25 clad, which showed minimal transmission losses of 0.7 dB/m at 5.5 μm. Their IR spectrum, however, con- tained a strong (23 dB/m) absorption band centered at 4.01 μm, due to the presence of SH groups. As 2 S 1.5 Se 1.5 glass fibers have a longer wavelength transmission limit than purely sulfide fibers and better mechanical properties than As 2 Se 3 fibers [3]. Replacing 30% of the sulfur in As 2 S 3 by selenium shifts the mul- tiphonon absorption edge by about 1 μm. At higher Se contents, the shift is even more pronounced. The purpose of this work was to prepare As 2 S 1.5 Se 1.5 glass with lower impurity levels and to fabricate optical fibers with lower transmission losses than in our previ- ous study [3]. EXPERIMENTAL In our experiments, we prepared glasses of two compositions, which were then used to draw core–clad optical fibers. The fibers were characterized by absorp- tion, numerical aperture, and bending strength mea- surements. As 38 S 25 Se 37 (core) and As 38 S 27 Se 35 (clad) glasses were prepared by melting appropriate mixtures of puri- fied arsenic monosulfide, arsenic, and selenium in silica ampules sealed off under vacuum. To reduce contami- nation from the ambient atmosphere, the starting reagents were introduced into the reactor by evapora- tion from intermediate ampules in an all-welded sys- tem. The melt was homogenized at 750°C for 7 h in a rocking muffle furnace and then furnace-cooled at a rate of 1 K/min. The preforms were 26 mm in diameter and about 120 mm in height. Transmission spectra were mea- sured between 2.0 and 25 μm (5000–400 cm –1 ) on a Bruker IFS-113V Fourier transform IR spectropho- tometer. Optical fibers about 150 m long were prepared by the double-crucible method. The core/clad diameters were 300/400 or 200/400 μm. During drawing, no glass crystallization was detected. The fibers were protected by a double coating consisting of tetrafluoroethyl- ene/1,1-difluoroethylene copolymer (F-42) and polyvi- nyl chloride (PVC) layers. Both layers were applied during drawing. Optical losses were measured using a standard two- point technique (cut-off method) [4] with an accuracy High-Purity As 2 S 1.5 Se 1.5 Glass Optical Fibers M. F. Churbanov*, V. S. Shiryaev*, I. V. Skripachev*, G. E. Snopatin*, V. G. Pimenov*, S. V. Smetanin*, R. M. Shaposhnikov*, I. E. Fadin*, Yu. N. Pyrkov**, and V. G. Plotnichenko** * Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, ul. Tropinina 49, Nizhni Novgorod, 603950 Russia ** Fiber Optics Research Center, General Physics Institute, Russian Academy of Sciences, ul. Vavilova 38, Moscow, 117756 Russia e-mail: shiryaev@ihps.nnov.ru Received June 21, 2001 Abstract—Core–clad optical fibers were fabricated from high-purity As 2 S 1.5 Se 1.5 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.