The subwavelength imaging phenomenon in Maxwell’s fisheye lens with one drain has been reported previously. In this paper, we theoretically find that coherent perfect absorbers (CPAs) perform well in generalized Maxwell’s fisheye (GMFE) lenses. Such CPAs are embedded inside the GMFE lenses to absorb the incoming coherent waves. They can be served as drains and dramatically improve the resolution of images in the GMFE lenses. In particular, they can be applied to realize the subwavelength imaging. We also study the multiple imaging characteristics of GMFE lenses with several CPAs in wave optics. Full-wave simulations were performed to verify the imaging functionalities.
Acoustic waves have been widely applied in communications, medical treatment, military, and other aspects. In this Letter, we explore acoustic imaging properties of three-dimensional Maxwell's fish-eye lens (3D-MFEL) with elevated refractive index profile, the analytical and numerical results show that a 3D-MFEL based on solid immersion mechanism can achieve super-resolution imaging without chromatic aberration. In addition, introducing vortex waves into the 3D-MFEL, we further explore the super-resolution imaging properties in reconstructing vortex waves. The valid combination of 3D-MFEL and solid immersion mechanism provides a meaningful way for super-resolution imaging, which also paves a way forward for future designing and manufacturing in acoustic super-imaging systems.
Vibration in thin plates is a common issue in structural engineering that can significantly impact the performance of structures. One crucial objective is to control vibration intensity. Metamaterials offer a promising solution to this challenge. Herein, a multiband elastic waveguide cloak that uses metamaterials and does not require active components or complex designs is introduced. By converting flexural waves to waveguide‐trapped waves, a cloaking region with negligible vibration can be created. Herein, independent mode conversion channels for elastic waves, which could lead to new approaches to modulating elastic waves, are discovered. The experiment results are in excellent agreement with the numerical simulation results and demonstrate a waveguide cloaking effect. This design has a compact structure and exhibits multiband performance, making it highly suitable for vibration control in various scenarios, including the aerospace industry, bridge engineering, and shock‐absorbing platforms.
In this paper, we devise a pentamode metamaterial plate exhibiting topological characteristics. By organizing pentamode metamaterial structural elements, topological boundary states are attained, effectively safeguarding propagation of elastic waves. Moreover, based on the numerical simulation model, we employ a polymer to fabricate a macro-scale specimen via additive manufacturing. Through assessing the vibrational response of the sample, we corroborate its topological attributes in governing elastic wave transmission. This discovery paves the way for a novel approach to manipulating acoustic/elastic waves employing pentamode metamaterials.
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