Low-noise 1480-nm pumped L-band erbium-doped fibre amplifiers incorporating a bypass isolator

We demonstrate experimentally that a 1480 nm pumping scheme can be efficiently used instead of 980 nm for low-noise amplification with long wavelength band erbium-doped fibre amplifier. A bypass isolator allows the propagation of the 1480 nm light in the forward-pumped first-stage amplifier while blocking the backward propagating amplified spontaneous emission from the second-stage amplifier. Pumping at 1480 nm instead of 980 nm improves significantly the gain of the amplifier, at the price however of some noise figure penalty. Low noise figures of 5.0–5.8 dB are obtained from 1569 to 1605 nm for −7 dBm signal power.