Optomechanics of random media

Using light to control the movement of nanostructured objects is a great challenge. This challenge involves fields like optical tweezing, Casimir forces, integrated optics, biophysics, and many others. However, when the complexity of the light-activated devices increases, disorder unavoidably occurs and induces a number of effects, such as multiple-scattering, diffusion, and the localization of light. We show that these effects radically enhance the mechanical effect of light. We determine theoretically the link between optical pressure and the light diffusion coefficient and unveil that optical forces and their statistical fluctuations reach a maximum at the onset of the photon localization. Disorder may thus be exploited for increasing the mechanical action of light on complex objects.