Low-noise and gain-flattened fluoride-based Er ³⁺ -dopedfibre amplifier pumped by 0.97 µm laser diode

The authors demonstrate a gain-flattened Er3+-doped fluoride fibre amplifier with low noise amplification characteristics which employs 0.97 µm laser diode pumping. Excellent flat amplification is achieved with an average signal gain of 12.5 dB and a gain excursion of < 1.0 dB, with a noise figure of 4.7 ± 0.2 dB for an 8 channel WDM signal in the 1532–1560 nm wavelength region. The authors confirm that an Er3+-doped fluoride fibre can be excited effectively to the 4I11/2 level by shifting the pump wavelength from 0.98 to 0.97 µm.