Preparation and characterization of the As₄₀Se₆₀ and As_38.8Se_61.2 glasses with high quality for the single mode IR glass fiber

In this paper, high quality chalcogenide infrared-transmitting As₄₀Se₆₀ and As_38.8Se_61.2 glasses were prepared and characterized for single mode glass fibers. In order to obtain high purity glasses, the starting materials, As and Se (99.9999%), were purified using a distillation method, which required heat treatment under vacuum using silica tubes and a liquid N₂ trap system. As₄₀Se₆₀ and As_38.8Se_61.2 glasses are chosen as core and cladding, respectively. From the differential scanning calorimetry (DSC) results, the glass transition temperature (T_g) of the As₄₀Se₆₀ and As_38.8Se_61.2 glasses was 183 °C and 173 °C, respectively. Infrared transmission of the two glasses shows good transmittance over the range of 1-12 μm. There is a slight absorption in both glasses at ∼4.4 μm which is related to Se-H bonds. In order to measure the refractive index over the range of ∼2 -12 μm, prisms of 40 mm × 40 mm × 15 mm with 20° angles were made and were carefully polished. It was found that the refractive indices of As₄₀Se₆₀ were slightly higher than those of the As_38.8Se_61.2.