2D phononic-crystal Luneburg lens for all-angle underwater sound localization

Abstract

Phononic crystals are well known for acoustic wave manipulation which may have potential application in an underwater acoustic detection system. In this work, we design and simulate a two-dimensional Luneburg lens based on gradient-index (GRIN) phononic crystal that is composed of PLA-Air inclusion, and a novel application of GRIN phononic crystals is proposed to sound localization. The Luneburg lens has a broadband working range, from 1500 Hz to 7500 Hz, for acoustic wave focusing with sensitive directivity and signal-to-noise improvement. By searching maximum wave intensity’s position of the focusing beam, the propagating direction of an unknown sound wave can be directly recognized covering 360°. Besides, we redesign the conventional square-lattice Luneburg lenses using annular lattices for better performance. The annular-lattice Luneburg lens overcomes the weakness of configuration defect due to the square lattice. The numerical results show that the redesign Luneburg lenses have high accuracy for distance measurement from 5 m to 35 m through the triangulation location. In a word, this work tries to explore a novel application of phononic crystals in underwater acoustic positioning and navigation technology.

Broadband acoustic signal enhancement via gradient metamaterials coupled to crystals

“…Nejad [33] created an acoustic fiber with a higher refractive index than uniform air using cross-shaped phononic crystals. Ruan [34] and Ahmed Allam [35] constructed 2D and 3D phononic crystal focusing lenses based on the equivalent gradient refractive index feature possessed by gradient phononic crystals for applications in underwater acoustic focusing.…”

Three-Dimensional Gradient Metamaterial Devices Coupled with Phononic Crystals for Acoustic Enhancement Sensing

“…The properties of subwavelength phonon crystal (PC) arrays provide ideas for solving this problem. PC arrays can be constructed with the characteristics of high refractive index media [35][36][37]. Therefore, in this work, a device made from axisymmetric three-dimensional gradient metamaterials which incorporate phononic crystals (GAM-PC) is proposed, which has a gradient profile, a gradient plate thickness, and a gradient gap width along the axis of the wave propagation direction.…”

Underwater target passive acoustic localization method based on Hanbury Brown–Twiss interference

“…However, such waves are heavily attenuated in water and cannot penetrate the surface of the ocean; therefore, their use in underwater information transmission is challenging. In contrast to electromagnetic and optical electromagnetic waves, sound waves have the characteristic of slow attenuation in water, which is one of the main carriers for underwater long-distance information transmission (Diamant and Lampe, 2012; Li et al , 2022; Ruan and Liang, 2022). Therefore, acoustic localization uses the characteristics of sound waves to perform long-distance localization tasks and can be divided into active and passive localization methods.…”