title: Extraordinary absorption of sound in porous lamella-crystals.
abstract: We present the design of a structured material supporting complete absorption of sound with a broadband response and functional for any direction of incident radiation. The structure which is fabricated out of porous lamellas is arranged into a low-density crystal and backed by a reflecting support. Experimental measurements show that strong all-angle sound absorption with almost zero reflectance takes place for a frequency range exceeding two octaves. We demonstrate that lowering the crystal filling fraction increases the wave interaction time and is responsible for the enhancement of intrinsic material dissipation, making the system more absorptive with less material.
authors.affiliation: 1] Institute of Technology and Innovation, University of Southern Denmark, DK-5230 Odense, Denmark [2] Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Christensen
authors.affiliation: 1] Instituto de Investigación para la Gestión Integrada de zonas Costeras, Universitat Politècnica de València, Paranimf 1, 46730, Gandia, Spain [2] LUNAM Université, Université du Maine, CNRS, LAUM UMR 6613, Av. O. Messiaen, 72085 Le Mans, France.
authors.forename: V
authors.initials: V
authors.lastname: Romero-García
authors.affiliation: Instituto de Investigación para la Gestión Integrada de zonas Costeras, Universitat Politècnica de València, Paranimf 1, 46730, Gandia, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Picó
authors.affiliation: Instituto de Investigación para la Gestión Integrada de zonas Costeras, Universitat Politècnica de València, Paranimf 1, 46730, Gandia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Cebrecos
authors.affiliation: 1] ICFO Institut de Ciències Fotòniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain [2] ICREA - Institució Catalana de Reserca i Estudis Avançats, Passeig Lluís Companys 23, 08010 (Barcelona), Spain.
authors.forename: F J García
authors.initials: FJ
authors.lastname: de Abajo
authors.affiliation: Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: N A
authors.initials: NA
authors.lastname: Mortensen
authors.affiliation: Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Willatzen
authors.affiliation: Instituto de Investigación para la Gestión Integrada de zonas Costeras, Universitat Politècnica de València, Paranimf 1, 46730, Gandia, Spain.
authors.forename: V J
authors.initials: VJ
authors.lastname: Sánchez-Morcillo
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