title: Formation of high-order acoustic Bessel beams by spiral diffraction gratings.
abstract: The formation of high-order Bessel beams by a passive acoustic device consisting of an Archimedes' spiral diffraction grating is theoretically, numerically, and experimentally reported in this paper. These beams are propagation-invariant solutions of the Helmholtz equation and are characterized by an azimuthal variation of the phase along its annular spectrum producing an acoustic vortex in the near field. In our system, the scattering of plane acoustic waves by the spiral grating leads to the formation of the acoustic vortex with zero pressure on axis and the angular phase dislocations characterized by the spiral geometry. The order of the generated Bessel beam and, as a consequence, the size of the generated vortex can be fixed by the number of arms in the spiral diffraction grating. The obtained results allow for obtaining Bessel beams with controllable vorticity by a passive device, which has potential applications in low-cost acoustic tweezers and acoustic radiation force devices.
authors.affiliation: LUNAM Université, Université du Maine, CNRS, LAUM UMR 6613, Avenue O. Messiaen, 72085 Le Mans, France.
authors.forename: Noé
authors.initials: N
authors.lastname: Jiménez
authors.affiliation: IGIC, Universitat Politècnica de València, Paranfimf, E-46730 Grao de Gandia, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Picó
authors.affiliation: IGIC, Universitat Politècnica de València, Paranfimf, E-46730 Grao de Gandia, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Sánchez-Morcillo
authors.affiliation: LUNAM Université, Université du Maine, CNRS, LAUM UMR 6613, Avenue O. Messiaen, 72085 Le Mans, France.
authors.forename: V
authors.initials: V
authors.lastname: Romero-García
authors.affiliation: IUMPA, Universitat Politècnica de València, Camino de Vera s/n, 46022 València, Spain.
authors.forename: L M
authors.initials: LM
authors.lastname: García-Raffi
authors.affiliation: ICREA, Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrasa, Barcelona, Spain.
authors.forename: K
authors.initials: K
authors.lastname: Staliunas