FWM and XPM in Er3+-doped silica and tellurite fibers

Fiber background materials determine the ligand field around erbium ions. The ligand field determines the broadening of the absorption and emission spectrum of erbium ions. In the paper, analyses show that the linewidth of emission spectra of erbium doped fibers determines the 4f shell electronic correlation. Furthermore, it influences the electronic dipole-dipole interaction and the resonantly enhanced nonlinearity of erbium ions. The wider the emission spectrum is, the weaker the electronic interrelation of erbium ions and the weaker the resonantly enhanced nonlinearity. Erbium doped silica based fiber and erbium doped tellurite based fiber are with different emission linewidths. They correspond to different level of resonantly enhanced nonlinearities. Comparison of crosstalk induced by FWM and XPM in these two kinds of fibers has been done using semiclassical theory. The results show that erbium doped tellurite fiber corresponds to much smaller crosstalk than erbium doped silica fiber, and therefore is more appropriate for DWDM communications.