A route to robust double pulse excitability in optically injected semiconductor lasers

We present and analyse a three-dimensional model for a quantum dot semiconductor laser with optical injection. This model describes recent experimental single and double excitable intensity pulses, which are related to a central saddle-node homoclinic bifurcation as in the Adler equation. Double pulses are related to a period doubling bifurcation and occur on the same homoclinic curve as single pulses. The bifurcation scenario consolidating single and double excitable pulses is described in detail.