The noise figures of a 100m long Er3+-doped fibre amplifier pumped in the 800 nm band were investigated. Noise figures of 3·9·4·7dB were obtained at 1535 nm with input pump wavelengths of 818–824 nm, corresponding to spontaneous emission factors of 1·23-1·48. These values are similar to those obtained using a 1480 nm pump scheme. The noise figure at 1552 nm was about 4dB and the spontaneous emission factor was 1·26.
- Optical fibres