Nondiffracting pulses in anisotropic materials

Various localized electromagnetic and acoustic waves, nondiffracting fields, and other directed-radiation beams are of great current interest. The authors present a new category of nondiffracting acoustic waves that propagate in either isotropic or anisotropic solid media. The nondiffracting pulses are spectral generalisations of the monochromatic conical waves, a property which provides novel insight into the physical analysis and the actual preparation of such localized space-time fields. The nondiffracting pulses obtained via the space-frequency synthesis of nondiffracting conical waves are illustrated with the help of broadband X-like waves for which explicit expressions are derived. The relation of these fields to the previously known localized solutions is established. The nondiffracting acoustic pulses in anisotropic substrates offer several new design opportunities in various applications