Role of random frequency fluctuations in radiation line shaping for semiconductor laser under pseudorandom pulsed operation

It is well known that, on the creation of dynamically single-mode distributed feedback (DFB) heterolasers (HL), the principal and physically inevitable factor restricting the fiber-optics links transmission length is the finite spectrum spread of the HL. Due to the chromatic dispersion of fiber resulting in a relative temporal shift of spectral signal components, the emission lineshape is distorted which leads, in its turn, to the transmission malfunction. This paper presents for the first time the numerically calculated results for the estimation of frequency fluctuations role in shaping of a single-mode HL radiation spectrum under the current pseudorandom pulsed modulation. We apply to the analysis the novel approach that has been earlier used to study the dynamics and spectral density of the HL intensity fluctuations under pulsed operation.