Photoacoustic ultrasound sources from diffusion-limited aggregates

Metallic diffusion-limited aggregate (DLA)films are well-known to exhibit near-perfect broadband optical absorption. We demonstrate that suchfilms also manifest a substantial and relatively material-independent photoacoustic response, as a consequence of their randomnanostructure. We theoretically and experimentally analyze the photoacoustic phenomena in DLAfilms and show that they can be used to create broadband air-coupled acoustic sources. These sources are inexpensive and simple to fabricate and work into the ultrasonic regime. We illustrate the device possibilities by building and testing an optically addressed acousticphased array capable of producing virtually arbitrary acoustic intensitypatterns in air.

Source: Applied Physics Letters - November 3, 2016 Category: Physics Authors: Krutik Patel, Morgan Brubaker, Alexander Kotlerman, Robert Salazar, Eli Wolf and David M. Weld Source Type: research