Analyses show that the linewidth of emission spectra of EDFA determines the 4f shell electronic correlation. It influences the electronic dipole-dipole interaction and the resonantly enhanced nonlinearity of erbium ions. Si-EDFAs and Te-EDFAs,with different emission linewidths,correspond to different level of resonantly enhanced nonlinearities. Comparison of crosstalk induced by four-wave mixing and cross-phase modulation in Si-EDFAs and Te-EDFAs is carried out using semiclassical theory. The results show that Te-EDFA corresponds to much smaller crosstalk than Si-EDFA,and therefore is more appropriate for DWDM communications.