Approximate dynamic model for evaluating distortion in a semiconductor laser under overmodulation

Overmodulation of a directly modulated semiconductor laser causes distortion in the optical signal. This distortion can be analyzed, in a first approach, using the model of a static limiter for the laser. In this letter, the dynamic effects in overmodulation of a semiconductor laser are addressed for a sinusoidal modulating current and an improved model is proposed by introducing an hysteresis. A time delay is taken into account for evaluating additional dynamic distortion arising when the optical intensity rises above threshold.