Practical realization of a sub-λ/2 acoustic jet

Daniel Veira Canle, Tuukka Kekkonen, Joni Mäkinen, Tuomas Puranen, Heikki J. Nieminen, Antti Kuronen, Sami Franssila, Tapio Kotiaho, Ari Salmi*, Edward Hæggström

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)
119 Downloads (Pure)


Studies in optics and acoustics have employed metamaterial lenses to achieve sub-wavelength localization, e.g. a recently introduced concept called ‘acoustojet’ which in simulations localizes acoustic energy to a spot smaller than λ/2. However previous experimental results on the acoustojet have barely reached λ/2-wide localization. Here we show, by simulations and experiments, that a sub-λ/2 wide localization can be achieved by translating the concept of a photonic jet into the acoustic realm. We performed nano- to macroscale molecular dynamics (MD) and finite element method (FEM) simulations as well as macroscale experiments. We demonstrated that by choosing a suitable size cylindrical lens, and by selecting the speed-of-sound ratio between the lens material(s) and the surrounding medium, an acoustic jet (‘acoustic sheet’) is formed with a full width at half maximum (FWHM) less than λ/2. The results show, that the acoustojet approach can be experimentally realized with easy-to-manufacture acoustic lenses at the macroscale. MD simulations demonstrate that the concept can be extended to coherent phonons at nanoscale. Finally, our FEM simulations identify some micrometer size structures that could be realized in practice. Our results may contribute to starting a new era of super resolution acoustic imaging: We foresee that jet generating constructs can be readily manufactured, since suitable material combinations can be found from nanoscale to macroscale. Tight focusing of mechanical energy is highly desirable in e.g. electronics, materials science, medicine, biosciences, and energy harvesting.

Original languageEnglish
Article number5189
Number of pages6
JournalScientific Reports
Issue number1
Publication statusPublished - 1 Dec 2019
MoE publication typeA1 Journal article-refereed




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