title: Phoxonic Hybrid Superlattice.
abstract: We studied experimentally and theoretically the direction-dependent elastic and electromagnetic wave propagation in a supported film of hybrid PMMA (poly[methyl-methacrylate])-TiO2 superlattice (SL). In the direction normal to the layers, this one-dimensional periodic structure opens propagation band gaps for both hypersonic (GHz) phonons and near-UV photons. The high mismatch of elastic and optical impedance results in a large dual phoxonic band gap. The presence of defects inherent to the spin-coating fabrication technique is sensitively manifested in the band gap region. Utilizing Brillouin light scattering, phonon propagation along the layers was observed to be distinctly different from propagation normal to them and can, under certain conditions (SL thickness and substrate elasticity), reveal the nanomechanical properties of the constituent layers. Besides the first realization of unidirectional phoxonic behavior, hybrid (soft-hard) periodic materials are a promising simple platform for opto-acoustic interactions and applications such as filters and Bragg mirrors.
authors: ‡Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors: Elena
authors: E
authors: Alonso-Redondo
authors: §Department of Inorganic Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany.
authors: Hannah
authors: H
authors: Huesmann
authors: ⊥LDOM, Département de Physique, Faculté des Sciences, Université Mohamed I, 60000 Oujda, Morocco.|#Institut d'Électronique, de Microélectronique et de Nanotechnologie (IEMN), UMR-CNRS 8520, UFR de Physique, Université de Lille 1, 59655 Villeneuve d'Ascq, France.
authors: El-Houssaine
authors: el-H
authors: El Boudouti
authors: §Department of Inorganic Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany.
authors: Wolfgang
authors: W
authors: Tremel
authors: #Institut d'Électronique, de Microélectronique et de Nanotechnologie (IEMN), UMR-CNRS 8520, UFR de Physique, Université de Lille 1, 59655 Villeneuve d'Ascq, France.
authors: Bahram
authors: B
authors: Djafari-Rouhani
authors: ‡Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors: Hans-Juergen
authors: HJ
authors: Butt
authors: ‡Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.|||Department of Materials Science, University of Crete and IESL/FORTH, 71110 Heraklion, Greece.
authors: George
authors: G
authors: Fytas
keywords: Brillouin spectroscopy; band gap; hybrid superlattices; phononics; photonics