Investigation of signal excited-state absorption in bismuth-based erbium-doped fiber amplifier

Abstract

Signal excited-state absorption (ESA) in a bismuth oxide-based erbium-doped fiber (EDF) amplifier was investigated in numerical and experimental ways. The signal ESA cross-section of the bismuth oxide-based EDF was first measured by using a especially devised numerical-prediction technique that can give an accurate value for an arbitrary EDF length. Using a range of numerical simulations based on the measured signal ESA cross-section as well as experimental measurements, the signal ESA’s impact on the gain and noise figure was investigated. The signal ESA reduces the amplification bandwidth by ∼7 nm compared with that of the theoretical gain bandwidth that can be obtained without signal ESA. The longer wavelength limit of the amplification band was estimated to be ∼1632 nm.