Distinction between multimoded and singlemoded self-pulsations in DFB lasers

DFB lasers with split contacts are shown, by large signal dynamic modelling, to self-pulsate at gigabit frequencies. Two different self-pulsation schemes are discussed: where the laser switches between the higher and lower stop band modes, and where the laser pulsates around a single mode. The second scheme can yield self-pulsation frequencies beyond 20 GHz. Comparisons are made with experimental results.