Conditionally extraordinary transmission in periodic parity-time symmetric phononic crystals. (November 2019)

• Record Type: Journal Article
• Authors: Yi, Jianlin; Negahban, Mehrdad; Li, Zheng; Su, Xianyue; Xia, Rongyu
• Is Part Of: International journal of mechanical sciences. Volume 163(2019)
• Publication Date: 2019-11
• Subjects: Parity-time symmetry -- Unidirectional zero reflection -- Extraordinary transmission -- Phononic crystals -- Interface response theory; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2019.105134
• Languages: English
• ISSNs: 0020-7403

Abstract

Highlights: The parity-time symmetry is introduced into locally resonant phononic crystal. Coalesced band of the parity-time symmetric phononic crystal is illustrated. The extraordinary transmission and unidirectional zero reflection can be realized simultaneously in PT -symmetric phononic crystal system. The relation between extraordinary transmission points and coalescence points is pointed out. It is pointed out number of unit cell of phononic crystal affects the occurrence of extraordinary transmission. Abstract: Parity-time ( PT ) symmetry originating from quantum mechanics has extended to other branches, such as optics and acoustics. In acoustics, the studies have mainly focus on fluids, such as air, and, in particular, they have not involved periodicity of structure, as seen in phononic crystals (PC). The current work introduces loss-gain PT symmetry into periodic elastic PC lattice systems that can simultaneously realize unidirectional zero reflection and extraordinarily high transmission under the condition: a certain number of unit cells of PC. In particular, it is shown that the infinite periodic PT symmetric PC ( PT -S-PC) shows coalescence of band structure. Interface response theory of the system is used to investigate the scattering matrix of finite PT -S-PCs. The results show that the transmittance is extraordinarily high, reaching hundreds, at the frequency associated with the coalescence point of the infinite periodic PT -S-PC. The extraordinary transmission appears periodic-like with respect to the number of cells of the PT -S-PC system, and this extraordinary transmission resonance has an ultrahigh quality factor. Moreover, the scattering characteristics of the PT -S-PC system in the locally resonant band gap are explored. This work provides a new way to manipulate elastic waves and opens the path to design new devices, for example, for non-destructive testing. Graphical abstract: Image, graphical abstract