Noise figure limitation in ytterbium-codoped erbium-doped fiber amplifiers pumped at 1064 nm

Summary form only given. Erbium/ytterbium-doped optical fiber amplifiers (EYDFAs) are attractive because they convert the power available in 1064-nm neodymium-doped sources to 1550 nm. In many potential applications such as CATV, LAN, and WDM systems, an excellent noise figure (NF) is required. In 980-nm pumped erbium-doped fiber amplifiers (EDFAs), a 3-dB NF can be achieved. We show this is not always true in 1064-nm pumped EYDFAs.