Controllable switching of platicon propagation direction in normal-dispersion photonic-crystal microresonators

We demonstrate numerically that upon scanning the pump frequency, controllable switching of the platicon propagation direction (rotation switching) can be observed in normal-dispersion photonic-crystal microresonators. During the forward scan, platicon generation first occurs in the backward wave; as the pump frequency detuning increases, this state may transform into the forward-wave platicon regime. The parameter range for this phenomenon is determined: larger pump amplitudes require larger pump mode-splitting values. With a further increase in the pump amplitude, switching from the backward-wave breather to the forward-wave platicon takes place. The discussed switching effect is reversible: during the backward pump frequency scan, the forward-wave platicon transforms into a platicon or platicon breather in the backward wave. At sufficiently high pump amplitudes, the outcome of this process becomes probabilistic, depending on the particular realization of the input conditions.