From Technology Review :: The ability to create phonons and then steer them using laser beams could lead to a new generation of applications, say physicists ::
Zap an optical fibre with a couple of laser beams and the resulting interference pattern causes an interesting effect–it squeezes the material, an effect known as electrostriction. This creates a compression wave called a phonon, a packet of sound, which travels along the fibre.
Not to be outdone, phonons also influence light because they change the refractive index of the material. This bends light and alters its frequency, an effect known as Brillouin scattering.
After that, things get complicated…. Read on: http://www.technologyreview.com/view/428515/how-to-steer-sound-using-light/?nlid=nldly&nld=2012-07-17 OR: THE PHYSICS ARXIV BLOG Monday, July 16, 2012