Transmission-line laser modelling of semiconductor laser amplified optical communications systems

Previously, the transmission-line laser model (TLLM) has been used to simulate the optical noise characteristics of semiconductor lasers and semiconductor laser amplifiers in the time-domain. This paper shows that, with the addition of a suitable photodiode model, the baseband electrical noise characteristics of amplified optical systems can also be simulated with the TLLM. A simple theory of the baseband noise properties of a detected optical signal is presented and a photodiode model for the TLLM is developed. The baseband electrical noise spectra of travelling-wave, Fabry-Perot and DFB laser amplifiers are numerically simulated. This is a new approach to amplified optical communications system modelling. As an example, a 10 Gbit/s system is simulated, and the effects of the optical filter on the signal and the noise are investigated