Pump excited-state absorption in erbium-doped fibers

Abstract

Ground-state and excited-state absorption spectra covering the wavelength range of 450–1050 nm are presented for erbium-doped silica fibers with four different core codopants: GeO₂, GeO₂/B₂O₃, GeO₂/P₂O₅, and Al₂O₃. It is shown that the host glass influences the excited-state absorption spectra and that P₂O₅- or Al₂O₃-codoped fibers are the preferred choice for 514.5-, 655-, or 807-nm pump wavelengths owing to reduced pump excited-state absorption. However, excited-state absorption is still significant at the 807-nm wavelength. Pump wavelengths of 524, 532, and 980 nm appear ideal because of the strong ground-state absorption and lack of excited-state absorption.