Helilainete

Helilainete is a term used in acoustics to describe a class of wave phenomena in which acoustic waves acquire a helical, or corkscrew, phase structure as they propagate through certain media. The effect is analogous to optical orbital angular momentum but involves sound waves and often depends on the medium’s geometry, chirality, or engineered metamaterials that couple spin-like and orbital components of the wavefront.

Key mechanisms include propagation through chiral media, transmission along spiral waveguides, or interaction with metasurfaces that impart azimuthal phase twists. In such settings, the waves carry orbital angular momentum and exhibit phase singularities, leading to ring-shaped intensity profiles and the possibility of manipulating small particles or creating structured sound fields.

Generation and measurement rely on devices such as spiral phase plates, acoustic holograms, or arrays of transducers that convert planar waves into helical fronts. Detection methods often use interferometry, modal decomposition, or spatial polarization-analogue analyses to quantify the helical mode content and its stability in the presence of loss and scattering.

Applications proposed for helilainete include high-resolution imaging, nondestructive evaluation, acoustic tweezers for manipulating microscopic objects, and enhanced communications in noisy environments. Research is ongoing to improve robustness, scalability, and integration with existing acoustic systems, as well as to understand interactions with matter at microscopic scales.

See also: acoustic vortex, orbital angular momentum of sound, phononic crystals, metamaterials, spiral phase plate.