Dynamical model of directly modulated semiconductor laser diodes

We present a new dynamical model for a directly modulated semiconductor dio de applicable to systems in which the dynamical time scales of interest are longer than the round-trip time of light in the diode, Employing a multipl e scales analysis to simplify the familiar phenomenological equations, we f ind that the dynamical response of the diode can he described by time-depen dent reflection and transmission coefficients for the electric field and on e ordinary differential equation for the integrated carrier density, We do not assume that the photon and carrier densities are uniform along the diod e and do not need to calculate them explicitly at each point. Additionally, we need not restrict ourselves to only a small signal response. We justify the multiple scales analysis for parameters corresponding to typical struc tures through a comparison of the numerical solution of our results and a d irect numerical integration of the original phenomenological equations.