Phononic band–gap guidance of acoustic modes in photonic crystal fibers

International audience; The existence of guided elastic modes in a photonic crystal fiber for an arbitrary cross-section is demonstrated using waveguide finite element analysis. In particular, it is shown that band-gaps exist for guided elastic modes along the longitudinal fiber axis, and thus a photonic crystal fiber can be simultaneously a phononic crystal fiber. The introduction of a defect within the two-dimensional crystal leads to the formation of highly localized elastic waveguide modes that co-propagate in the same core volume as the guided optical mode. We consider the application of these properties to the suppression of stimulated Brillouin scattering, and to enhanced collinear acousto-optical interactions.