Influence of fiber nonlinearity on the fiber transfer function: Theoretical and experimental analysis

The influence of fiber nonlinearity on the fiber transfer function is inves tigated theoretically and experimentally. A rigorous expression for the tib er transfer function using a directly modulated semiconductor laser as opti cal transmitter is presented, Very good agreement of fiber transfer functio n between experimental data and theoretical predictions is achieved, Furthe rmore, the fiber parameter values extracted from fitting are the same as th ose obtained from relative intensity noise measurements, and the fiber nonl inearity coefficient value is compared with other published results. A thor ough physical explanation for the effect of fiber nonlinearity on the fiber transfer function at low-medium frequencies is provided. Results reveal th at in the anomalous dispersion regime the fiber nonlinearity enhances the h igh-pass behavior typical of the fiber transfer function using a directly m odulated laser operating at high bias current, shifts the transfer function dips toward higher frequency, and consequently leads to a larger bandwidth , Furthermore, it is shown that the fiber nonlinearity can provide partial or total compensation of the nonuniform frequency response at low-medium fr equencies resulting from a directly modulated laser operated at low bias cu rrent.