Leader : Doya Valérie
Technological platforms : Specialty optical fibres manufacture
Application to the control of modes thanks to the classical dynamics For several years, we have shown that guided optics is an ideal medium for the experimental study of Wave Chaos. Multimode optical fibers (radius R >> l) offer great versatility to probe the influence of different dynamic regimes introduced via the geometric on the wave behavior. We can thus have an all-optical billiard with either regular, chaotic or mixed classical dynamics, depending on the geometry of the cross section of the fiber. Our experiments developed in the optical fibers with truncated section (diameter truncation > R) showed the characteristic signatures of chaotic ray dynamics on the properties of the propagating modes. Thus, the "scar" modes with a spatial localizations of the field along an unstable periodic orbit, one of the holy grails of the community of wave chaos, were observed. We are currently interested in fibers with mixed dynamics (diameter truncation < R) combining regular and chaotic behavior in the geometric limit. This duality is reflected in the spectral properties and spatial distribution of the propagating modes and allows to discriminate families of modes in a highly multimode fiber. The selection of modes in such fibers is currently being exploited in the field of optical telecommunications for modal multiplexing. Indeed, we propose to use the regular modes as independent transmission channels. Their spatial location ensures both a reduced coupling with other modes of propagation and a simplified excitation. Numerical and experimental studies are currently underway. The control of modes can also be assured by acting on the active medium. Again, the optical fibers offer great versatility in allowing both the localized introduction of active ions in the silica or by exploiting the optical Kerr effect which appears for high optical power and / or long lengths of interaction. Thus, by controlling the spatial location of the gain in a fiber with a chaotic transverse cross section, we performed an efficient scar modes filtering by the gain. If a local non-linearity allows control of the modal behavior , what about a broader and more complex non-linearity as the optical Kerr effect ? This open question is related to the competition between the geometry of the environment and the non-linearity of its response.
Studies under development are :
Finally, to characterize the changes induced by a disturbance modal behavior, we plan to exploit the concept of quantum fidelity. Quantum fidelity is related to the measurement of the response of a subject to a quantum system perturbation. An experiment of interferences of guided optical waves in optical fibers can be used to perform a direct measurement of diffusion fidelity while characterizing the influence of disturbances on the propagation modes.
MOSAIQ, Physique Mésoscopique, Photonique, Fibres Optiques
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