New dynamic semiconductor laser model based on the transmission-line modelling method

A versatile semiconductor laser model has been developed by the addition of a frequency-dependent gain model to the transmission-line modelling (TLM) method. The model provides a sampled optical output waveform for a modulated laser, from which output spectra may be found. To minimise computing time, a technique of sampling below the optical frequency is introduced. The theoretical basis for this model is considered, and the results gained for a 300 μm cavity heterojunction laser are compared with those given by the solution of the rate equations.