Children often marvel at the power of lightning and thunder, a dazzling interplay between light and sound. With modern nanomaterials, photonics, and ultrasonics technologies, researchers are now translating the wonders of sound produced by optical interactions at the nanoscale into photoacoustic systems. Those systems have the potential to provide cost-effective molecular imaging and therapy in medicine.

Light can be used to both generate and detect sound. Several physical mechanisms can be used for sound generation, but the most common is photoacoustics. The photoacoustic effect was discovered more than 125 years ago by Alexander Graham Bell. 1 He created a device he called the photophone, and several derivative devices such as the spectrophone shown in figure 1(a), in which a rotating thin disk emitted sound when exposed to a focused beam of light. Absorbed optical energy heated part of the disk, which was physically displaced via thermal expansion. Displacements were...

You do not currently have access to this content.