We derive a low-dimensional dynamical system to describe a semiconductor laser with optical feedback. This model captures many features from the original time delayed dynamical system and explains the origin of the low-frequency instability observed in the time-delayed equation.
Huyet, G., Porta, P. A., Hegarty, S. P., McInerney, J. G., & Holland, F. (2000). Low-dimensional dynamical system to describe low-frequency fluctuations in a semiconductor laser with optical feedback. Optics Communications, 180(4), 339–344. https://doi.org/10.1016/S0030-4018(00)00732-X