For medical and analytical applications, step-index fibers based on synthetic silica are widely used. For special applications, high-OH all-silica fibers with excellent UV-transmission are commercially available, even at 180 nm. E'-centers with an absorption band around 215 nm, generated by the UV-light transported in these fibers, have to be taken into account. In addition to stable E'-centers, transient defects exist at room temperature, as well; therefore, the transmission at 215 nm wavelength depends on the operational conditions.
The newly developed fibers with different diameters (from 100 μm to 600 μm core) will have a reduced defect concentration at 215 nm. In addition, the transient defect concentration has been reduced, too. The variation between the two power levels (dark, light) depends on the fiber diameter: the value is less than 0.3 dB/2m or 30 mAU/2m for large core fibers, one magnitude of order better than the comparable UVM-fiber described above. The hydrogen-content of the new fibers is negligible; therefore, the long-term behavior of these fibers, from 100 μm to 600 μm core diameter, is significantly better. In addition to low-power deuterium-lamps, the UV-damage of these fibers has been studied with high-power pulsed UV-lasers at 193 nm wavelength. Using the standard high-OH UV-fibers and UVM-fibers for comparison, the damage results will be discussed in detail. In addition, the established system for quality control of these UV-fibers will be described.