experimental setup Our paper about incoherent triggering of excitable pulses in an injection locked semiconductor laser has appeared in Optics Letters. That is an excellent news from a scientific point of view but not only. This paper is also the first common publication with our collaborators in Cork, so congratulations and many thanks to them, in particular to Bryan Kelleher with whom we set up this collaboration. The paper somehow follows our initial demonstration of the control of excitable pulses but it shows a particularly fascinating feature of excitable systems which we did not really address in that paper.

The first difference with our previous work is that in this case we are working with quantum dot lasers. This may have implications, but it is not the most relevant point here. In fact, the same experiment could probably be run on quantum well lasers, but since this experiment was carried out in Cork and our colleagues there often use quantum dot devices for this kind of experiments, quantum dots were used. The main point is elsewhere though.

One of the most salient features of excitable systems is their capability to respond identically to any perturbation that brings them beyond their excitation threshold. That is of course true when the system is perturbed by a stronger perturbation, being pushed harder than necessary: the response just does not change. But what is particularly interesting is that the response also remains the same when the perturbation direction (in phase space) is not the most suitable one. Since excitable pulses in this system are essentially phase pulses, the most efficient direction is to push the system's phase. However, as we show in this paper, the system can also respond even when pushed in a direction (in phase space) which is really not the preferred one. In this case, we leverage the very attractive character of excitable orbits to obtain a laser pulse at the wavelength of the slave laser by applying to it an optical power pulse which is detuned by up to several nanometers. Therefore, we obtain from this setup not only the reshaping of an input pulse (whatever distorted input pulse will be reshaped into perfect orbit), but also wavelength conversion. This wavelength conversion is of course an incoherent process, and the only requirement for it to occur is that the input pulse should be strong enough to trigger an excitable response.

The paper is on our publications page and reports about Incoherent optical triggering of excitable pulses in an injection-locked semiconductor laser.