Acoustic Manipulation And Application Based On Resonance-type Metasurface

In recent years,acoustic metasurface,a new type of artificial structure with subwavelength size for manipulating acoustic waves,has shown wide application prospects due to the novel mechanism and the flexible structure.The acoustic metasurface has the characteristics of thinness,low cost,and flexible control,which is beneficial to the miniaturization and integration of acoustical components.The study of acoustic metasurface is of great significance for future acoustic absorption and convergence,acoustic imaging,and generation of special beams.In this dissertation,an acoustic hybrid resonance structure based on Helmholtz resonators is used to achieve high transmittance and flexible control of the phase shift.Through the design and arrangement of the metasurface units,the highly efficient acoustic components are realized.The research contents are as follows:(1)A focusing lens based on acoustic resonance structure is proposed.Through the reasonable arrangement of the metasurface units,the acoustic can be effectively focused.Since the thick of the units is only 1/10 of the wavelength,it can provide a high resolution and achieve a focusing effect that breaks through the diffraction limit.In this work,the influence of numerical aperture,focal length,and incident angle on the focusing effect is analyzed,and the focal length,spot size and focusing intensity are calculated by simulations.Finally,to solve the narrow bandwidth of resonant structure,a wide band acoustic focusing lens is proposed.(2)A device for generating vortex beams based on acoustic resonance metasurface is proposed.The principle of vortex beam generated bay metasurface and design is analyzed in detail.The frequency applicability and sector arrangement are studied.Then,by setting the radius of the metasurface and the number of the hybrid resonance units,the high-order vortex beams were generated.Finally,the required phase to generate the multiplexing vortex field is calculated by an iterative algorithm,and then discretizes it and loads onto the metasurface to generate the multiplexing vortex.To verify the feasibility of the proposed scheme,real-time demodulation of the generated multiplexing vortex field is also performed by the proposed structure.