We analyse the stochastic polarization fluctuations in a vertical cavity surface emitting laser (VCSEL) under the influence of electro-optical feedback and show that the dynamics can be modeled as a bistable system with time-delayed memory. Assuming an asymmetric potential, we show the existence of a regime in which the systems dynamic displays excitability. We calculate the relevant residence time distributions and correlation times and compare our system to a well known discrete model for excitability. Finally, we present experimental data that demonstrates excitable behaviour in the polarization dynamics of a VCSEL and, in particular, show the appearance of coherence resonance.
The polarisation dynamics of vertical cavity surface emitting lasers
(VCSELs) in the bistable regime is well described by Kramers theory
for noise induced transitions. By employing feedback, a memory mechanism can be introduced, which make the dynamics of the system
non-Markovian. Here we analyse theoretically and experimentally the
residence time distribution of the bistable systems in the presence
of noise and time-delayed feedback, using an opto-electronic feedback cycle for a VCSEL. We demonstrate and explain various non-exponential features of the residence time distribution using a continuous as well as a two-state model. Additionally we compare the results to an electronic Schmitt trigger, which represents an experimental realization of the two-state model.
We analyse theoretically and experimentally the residence time distribution of bistable systems in the presence of noise and time-delayed feedback. The feedback provides a memory mechanism for the system which leads to non-Markovian dynamics. We demonstrate and explain various non-exponential features of the residence time distribution using a two-state as well as a continuous model. The experimental results are based on a Schmitt Trigger where the feedback is provided by a computer generated delay loop and on a semiconductor laser with opto-electronic feedback.