Abstract EN:

« Wave chaos » is concerned with the study of waves in closed systems whose geometrical limit presents a chaotic dynamics. The latter is revealed, among other features, by the extreme instability of particular trajectories, namely periodic orbits. How do waves behave in a system whose geometrical limit shows a chaotic dynamics ? Under specific conditions, they can freeze the onset of the chaotic dynamics, and concentrate their energy in the vicinity of the unstable periodic orbits, thus allowing the existence of “Scar” modes, which exhibit localized maxima of intensity along these trajectories. The work presented here results from the will to actively control the odes of a chaotic system in order to experimentally enhance the “Scar” modes. We introduce a localized gain medium in a multimode optical fiber with a chaotic cross section, previously known as an ideal system for studying wave chaos. The spatial localization of the gain allows the control of the enhancement of a family of “Scar” modes, through a selective amplification. We present numerical simulations validating the physical process of amplification, followed by an experimental study that demonstrates the selective amplification of “Scar” modes in a multimode optical fiber.