Abstract

Relativistic electrons moving over a periodic metal grating can lead to an intriguing emission of light, known as Smith–Purcell radiation (SPR), the precursor of the free-electron laser. The speed of light plays a critical role in the far-field emission spectrum. Inspired by this photonic SPR, here we experimentally demonstrate a photoacoustic phased array using laser-induced shock waves. We observe acoustic radiation spectrum in the far field, perfectly predicted by a universal theory for the SPR. This scheme provides a tool to control the acoustic radiation in the near field, paving the way toward coherent acoustic wave generation and microstructure metrology.

© 2023 Chinese Laser Press

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