Scattering Properties of an Acoustic Anti-Parity-Time-Symmetric System and Related Fabry–Perot Resonance Mode

Abstract

The pursuit of artificial structures exhibiting unusual acoustic properties is a major scientific endeavor, in which anti-parity-time (PT) symmetry has been coming into view recent years. At the same time, with the emergence of new acoustic metamaterials, the classical Fabry–Perot resonance mode also exhibits fascinating scattering features similar to those of the anti-PT-symmetric system. We derive the generalized relation for the scattering parameters of an acoustic anti-PT-symmetric system with a transfer matrix, including conjugate bidirectional reflection coefficients and pure real feature of transmission coefficient. In the absence of the real or the imaginary (representing gain/loss) part of the refractive index, the anti-PT-symmetric system degrades into a pair of complementary media, resulting in the bidirectional total transmission. Moreover, a Fabry–Perot resonance mode exhibiting conjugate bidirectional reflection coefficients and a pure imaginary transmission coefficient has been demonstrated. Our results are meaningful for guiding the experimental test of an acoustic anti-PT-symmetric system and the design of associated bidirectional response prototype devices.

One-dimensional PT -symmetric acoustic heterostructure

“…One of the most intriguing developments in quantum mechanics over the past few decades has been the discovery of a non-Hermitian Hamiltonian ℋ that commutes with the parity-time (𝒫𝒯 ) operator, a property that leads to realenergy eigenvalues. [1][2][3] Recently, considerable efforts have been further motivated to investigate its classical analogy in photonics, [4][5][6][7][8][9][10][11][12] acoustics, [13][14][15][16][17][18][19][20][21][22][23] and many more areas [24][25][26][27] by means of interleaving balanced loss-gain regions. In contrast to the photonic gain that can be straightforwardly implemented in a locally controlled fashion through stimulated emission, which involves optical (electrical) pumping by an external source or via parametric processes, [28][29][30][31] no passive acoustic gain material exists in nature.…”

Total acoustic transmission in a honeycomb network empowered by compact acoustic isolator

“…This ability opens up a new method for routing sound waves and exhibits promising applications ranging from acoustic communication to energy transmission.Acoustic metamaterials provide fascinating opportunities for artificially manipulating the propagation of sound waves [1][2][3] . At this rate, they have potential for applications in fields such as acoustic cloaking 4-7 , parity-time symmetry [8][9][10][11][12] , supertunneling [13][14][15] , and logic gates 16,17 . In recent years, how to control the propagation of sound waves through arbitrary pathway in a network has been a very challenging subject.…”