Abstract
Acoustic vortices with subwavelength dimensions and tunable topological charge are theoretically and experimentally synthesized at distances far beyond the Rayleigh diffraction length of the source, using self-demodulation. A dual helical acoustic source is used to generate two primary confocal vortex beams at different frequencies and different topological charges. As a consequence of the conservation of angular momentum during nonlinear wave mixing, a self-demodulated vortex beam at the difference frequency emerges, keeping the spatial features of the primary vortex beams and a topological charge that is the difference of their topological charges. We report subdiffractive vortices the characteristic size of which is 18 times smaller than its wavelength at a distance 2.8 times the Rayleigh diffraction length. The generation and focusing of subwavelength vortices paves the way for long-range communication, biomedical, and wave-matter interaction applications.
BibTeX citation
@inproceedings{JimenezIEEE2021,
author = {Noé Jiménez and Joao Ealo and Ruben Dario Muelas-Hurtado and Aroune Duclos and Vicent Romero-García},
booktitle = {IUS 2021: IEEE International Ultrasonics Symposium. Xi'an, China. 11-16 September},
doi = {https://doi.org/10.1109/IUS52206.2021.9593797},
editor = {2021 IEEE International Ultrasonics Symposium (IUS)},
isbn = {ISBN: 978-84-87985-30-4},
month = {9},
organization = {Institute of Electrical and Electronics Engineers},
pages = {1-4},
publisher = {IEEE},
series = {Oral},
title = {Sub-Diffractive Acoustic Vortices by Nonlinear Mixing},
url = {https://ieeexplore.ieee.org/document/9593797},
year = {2021}
}