Ultrapurification of Raw Material of Silver Halide Optical Fibers in Reacting Chlorine Atmosphere

The material of silver halide was ultrapurified by horizontal zone melting purification in reacting chlorine atmosphere. The chlorine atmosphere was made by decomposed chlorocar-bon with low boiling point [CHnCl4-n(n=0,l,2)]. The purification parameters were as follows: temperature 450-500℃, speed of zone 0.2-0.8mm/min and the carrier gas Ar 80-160mL/min. Measurement results show that the infrared absorbance of silver halide will decrease as wavelength increases at 2.5-12.5μm (4000-800cm-1) after the ultrapurification. The silver halide fiber is a well transparent medium for transmitting middle infrared at 2.5-16μm (4000-600cm-1). Forurier transform infrared spectra (FTIR) show that the transmittance of the fiber is better at 3.3-16μm. The loss is 0.3-0.5dB/m at 10.6μm.