20 dB gain at 1.55 μm wavelength in 50 cm long Er3+-doped fluoride fibre amplifier

Abstract
A 20 dB gain is observed at 1.55 μm in a 50 cm long fluoride fibre containing 5000 ppm Er3+-ion in a core. A launched pump power of 57 mW was obtained using a 1.48 μm laser diode. Gain difference in the 1535–1563 nm wavelength region is less than 1 dB.