We experimentally demonstrate the first method to focus light inside disordered photonic metamaterials. In such materials, scattering prevents light from forming a geometric focus. Instead of geometric optics, we used multi-path interference to make the scattering process itself concentrate light on a fluorescent nanoscale probe at the target position. Our method uses the fact that the disorder in a solid material is fixed in time. Therefore, even disordered light scattering is deterministic. Measurements of the probes fluorescence provided the information needed to construct a specific linear combination of hundreds of incident waves, which interfere constructively at the probe.

OPG
doi.org/10.1364/oe.16.000067
Opt. Express

Vellekoop, I. M., van Putten, E. G., Lagendijk, A., & Mosk, A. (2008). Demixing light paths inside disordered metamaterials. Opt. Express, 16(1), 67–80. doi:10.1364/oe.16.000067