Coding Metasurface for Talbot Sound Amplification

The Talbot effect has found profound applications in a wide variety of research fields, facilitating the development of sensing, imaging, and lithography, among others. Taking advantage of the flexibilities offered by the bidimensional Talbot effect, we propose and experimentally demonstrate a 2-bit coding acoustic metasurface lens. It is capable of arranging the far-field wave-energy distribution and thus tailoring the passive amplification of wave pattern at positions away from the source. By simply adjusting two different types of embedded helicoid units and their layout in the metasurface lens to change the coding sequences, the intensity amplification factor and period of the self-image can be manipulated simultaneously within the same imaging plane. The proposed Talbot lens allows flexible far-field sound redistribution and enhancement. Along with the nonresonant nature, it may open possibilities in applications such as acoustic communication, sonography, and signal processing.