Interplay between two kinds of Hopf instabilities in thin-film systems

This study investigates a structure including two such films irradiated from one side. Such a bilayer system can be considered as the basic element of a multilayer structure determining the main features of the all structure on the one hand and as individual element transforming the light on the other hand. Superradiation of the film both in the direction of incident beam and in the back direction provides the delay feedback between separate films. This study reveals two mechanisms of Hopf instabilities in the described thin-film system. The first mechanism is connected with the existence of multistable steady-state characteristic due to the superradiance and local field correction, while the second is relevant to the excitement of Rabi oscillations. Arising pulsations are sustained by the delay feedback existing between two films. The threshold value of the feedback delay can be minimized by the proper choice of parameters and even reduced to zero in the case of Rabi oscillations excitement.