High-Gain L-Band Extended Fiber Amplifier Using Bismuth-Erbium Co-Doped Fiber

A high-gain L-band extended fiber amplifier using bismuth-erbium co-doped fiber is investigated. The pre-amplifier and the double-pass configuration are used to improve the gain performance. The achieved 20-dB gain bandwidth is 61 nm (1557~1618 nm) with a 3-dB flatness bandwidth of 35 nm (1565~1600 nm), maximum gain of 51.95 dB, and minimum noise figure of 4.17 dB.