TRANSMISSION-LINE LASER MODELING 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. The 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 photodiode model for the TLLM is developed. The baseband electrical noise spectra of travelling-wave, Fabry-Perot and DFB laser amplifiers are numerically simulated, and the travelling-wave laser amplifier spectrum is in excellent agreement with simple theory. This new approach to amplified optical communications system modelling allows the effects of different optical and electrical filters on the signal and the noise to be studied simultaneously over a wide bandwidth. 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.