title: Broadband Focusing Acoustic Lens Based on Fractal Metamaterials.
abstract: Acoustic metamaterials are artificial structures which can manipulate sound waves through their unconventional effective properties. Different from the locally resonant elements proposed in earlier studies, we propose an alternate route to realize acoustic metamaterials with both low loss and large refractive indices. We describe a new kind of acoustic metamaterial element with the fractal geometry. Due to the self-similar properties of the proposed structure, broadband acoustic responses may arise within a broad frequency range, making it a good candidate for a number of applications, such as super-resolution imaging and acoustic tunneling. A flat acoustic lens is designed and experimentally verified using this approach, showing excellent focusing abilities from 2 kHz and 5 kHz in the measured results.
authors: State Key Laboratory of Millimeter Waves, Department of Radio Engineering Southeast University, Nanjing 210096, People's Republic of China.
authors: Gang Yong
authors: GY
authors: Song
authors: State Key Laboratory of Millimeter Waves, Department of Radio Engineering Southeast University, Nanjing 210096, People's Republic of China.
authors: Bei
authors: B
authors: Huang
authors: State Key Laboratory of Millimeter Waves, Department of Radio Engineering Southeast University, Nanjing 210096, People's Republic of China.|College of Science, Nanjing University of Posts and Telecommunicaitons, Nanjing 210023, People's Republic of China.
authors: Hui Yuan
authors: HY
authors: Dong
authors: State Key Laboratory of Millimeter Waves, Department of Radio Engineering Southeast University, Nanjing 210096, People's Republic of China.
authors: Qiang
authors: Q
authors: Cheng
authors: State Key Laboratory of Millimeter Waves, Department of Radio Engineering Southeast University, Nanjing 210096, People's Republic of China.
authors: Tie Jun
authors: TJ
authors: Cui