Institut Langevin, ESPCI ParisTech, France.
Phys Rev Lett. 2011 Aug 5;107(6):064301. doi: 10.1103/PhysRevLett.107.064301. Epub 2011 Aug 3.
We prove experimentally that broadband sounds can be controlled and focused at will on a subwavelength scale by using acoustic resonators. We demonstrate our approach in the audible range with soda cans, that is, Helmholtz resonators, and commercial computer speakers. We show that diffraction-limited sound fields convert efficiently into subdiffraction modes in the collection of cans that can be controlled coherently in order to obtain focal spots as thin as 1/25 of a wavelength in air. We establish that subwavelength acoustic pressure spots are responsible for a strong enhancement of the acoustic displacement at focus, which permits us to conclude with a visual experiment exemplifying the interest of our concept for subwavelength sensors and actuators.
我们通过使用声谐振器实验证明了宽带声音可以在亚波长尺度上被任意控制和聚焦。我们在可听范围内使用易拉罐（即亥姆霍兹谐振器）和商业计算机扬声器演示了我们的方法。我们表明，在易拉罐的集合中，衍射受限的声场可以有效地转换为亚衍射模式，并且可以通过相干控制这些易拉罐来获得在空气中像 1/25 波长一样薄的焦点。我们确定亚波长声压点是在焦点处产生强烈声位移增强的原因，这使我们能够通过一个视觉实验来说明我们的概念对于亚波长传感器和执行器的兴趣。
