Transient characteristics between periodic attractors stabilized by OPF method in a laser diode

Transition times among different stabilized periodic attractors in a chaotic laser diode, which are achieved with the HFI control method by applying a step-function signal to a modulation parameter, are typically tens of ns. These are longer than typical full round times in the stabilized periodic attractor. In order to shorten the transition time, Occasional Proportional Feedback (OPF) technique was applied in a laser diode for the first time. This technique requires the current feedback, which is proportional to the deviation of the chaotic output of the laser from the orbit, to stabilize into a certain Unstable Periodic Orbit (UPO), which exists inside the chaos attractor. We applied this control method at the poincare cross-section of a chaos attractor. We calculated the coordinates of the UPO, to which the chaotic attractor is stabilized, in the poincare cross-section, and found linear control parameters necessary for approaching to the UPO. We stabilized diode laser chaos to the periodic state of period-I or period-6 by OPF. From a statistical distribution of the transition times obtained for a final state of period-1, the average transition time is estimated to approximately 17.5ns, which is shorter than the time constant obtained with HFI for the similar conditions.