An L-band Erbium-doped fibre amplifier consisting of a length of dual-core fibre is reported. It has a flat gain of 12.1dB from 1565nm to 1615nm with a maximum gain variation of 0.6dB, and noise figure less than 3.9dB. We have a good corroboration between the theoretical simulations and the experimental results to show that the coupling coefficient between two cores can be increased with over the wavelength range 1550 nm to 1620 nm by adjusting the core-to-core spacing and core parameters to compensate for the gain decay due to erbium alone greater than the wavelength 1550 nm.
We show that a dual-core fiber can function as a wavelength selector for applications in Dense WDM systems. The fiber consists of an Erbium-doped core and an undoped core. The principle of operation relies on the large nonlinear effect of the Er-doped core when it is pumped by a 980nm laser diode. The selection of wavelength is achieved by adjusting the pump power launched into the doped core. Wavelengths with spacing of 1nm can be selected with crosstalks as low as 35dB.