Low-OH all-silica fiber with broadband transparency and radiation resistance in the UV region

Abstract

New step-index all-silica fibers with high-transparency in the whole spectral region from DUV (200nm) to IR (2200 nm) will be introduced. The light-guiding core-material consists of high-purity silica, especially with low-OH content of less than 10 ppm. In UV region, the losses are mainly influenced by Rayleigh scattering and electronic transitions leading to the Urbach-tail. On the other hand, the losses in the IR region are limited by traces of OH-groups (in the order of approx. 2 ppm) and fundamental vibration-bands. The fibers possess high resistance against UV radiation in spectral region of interest, which is comparable to high-OH all-silica fibers specially developed for UV-application below 250 nm. The properties of the new fiber in respect to basic attenuation and spectral damage in the UV-region will be discussed, in comparison to high-OH fibers, based on the same measurement-technique.