Underwater Focusing of Sound by Umklapp Diffraction

Scholte modes that are localized between a submerged axisymmetric structured elastic plate and surrounding fluid can undergo mode conversion via Umklapp diffraction into radiative modes; this response is verified by experiments show focusing of underwater sound across broad range frequencies. The diffracted beams, form cone, engineered to exist at desired spatial position, associated with an abrupt change in the patterning plate. These structures take grooves present only on one side plate, yet phenomena achieved both sides, even as viewed from flat surface.