${\hbox {Er}}^{3+}-{\hbox {Tm}}^{3+}$ -Codoped Tellurite Fiber Amplifiers for WDM Systems: A Theoretical Analysis of BER and Bandwidth

WDM systems cascaded by Er³-Tm³⁺-codoped tellurite fiber amplifiers pumped by 800- and 980-nm lasers are analyzed for the first time in this paper. We use an amplifier model based on propagation and population-rate equations that are solved numerically using the Runge-Kutta algorithm and Newton´s iterative method. In addition to analyzing the performance of the 800-nm pump, we also study the performance improvement after adding a new pump of 980 nm. With this new 980-nm pump, channels in the 1420-1620-nm wavelength region can reach a bit error rate (BER) less than 1times10^-9, with a transmission distance of 400 km.