ULTRAVIOLET-ABSORPTION MEASUREMENTS IN SINGLE-MODE OPTICAL-GLASS FIBERS

Accurate ultraviolet absorption measurements are reported in telecommunication single-mode optical fibers in the range from 280 to 600 nm (4.4-2.1 eV) using a cutback method. An absorption peak at 325 nm (3.8 eV) and an absorption edge near 290 nm (4.3 eV) are attributed to features seen in preform spectra. We suggest that fiber and preform absorption spectra are generally the same and do not find that there is any dependence in the absorption on the fiber dimensions. The effects of preparation for second harmonic generation on fiber absorption are also discussed.