New fluoroindate glass compositions

The limits of glass formation of new fluoroindate glass compositions have been determined for the basic systems InF₃–BaF₂–GdF₃−20ZnF₂−20SrF2–2XF_n where × = Na, La and InF₃–BaF₂−20ZnF₂−20SrF₂−2GdF₃–XF_n, where × = Ca and Y. The incorporation of small amounts of GaF₃ and/or GdF₃ increases strongly the thermal glass stability. All the fluoroindate compositions studied are highly transparent in the mid-infrared range; their transmission edge is shifted beyond 7 μm and the theoretical attenuation coefficient, extrapolated at the CO laser wavelength emission, is typically α = 100 dB/km. Large bulks and preforms have been prepared allowing the drawing of optical fibers.