Strong Collimated Emission Enhancement by Acoustic Metasurfaces

To realize an ``acoustic laser'', enhanced emission of a source of plane waves of sound is important, but because such sources possess a large surface area and thus high reflection loss, amplifying emission is difficult. With this in mind, the authors design and fabricate a high-$Q$ acoustic surface that incorporates a sound-plane-wave source, and with appropriate structural parameters yields strongly enhanced emission. This work suggests an inventive method to create high-intensity collimated sound beams, which should see application in sound manipulation and nonlinear acoustics.