ORIGINS OF SCATTERING CENTERS IN ZRF4-BASED INFRARED FIBERS, AND REDUCTION OF LOSS

The minimum loss of current fluoride fibres is dominated by wavelength independent scatter, and it is of great importance to identify its origin. Techniques have been developed to locate and analyse scattering centres, and over twenty different types of defect have been characterised. By improved processing, many types of centres, including the most serious, crystals and bubbles, have greatly reduced in frequency. As a result, the minimum fibre loss has been decreased to 0.65 dB/km, due mainly to decrease in extrinsic scatter loss to only 0.3 dB/km.