Measuring the spatial extent of individual localized photonic states
  We measure the spatial extent of individual localized photonic states in a slow-light photonic crystal waveguide. The size of the states is measured by perturbing each state individually through a local electromagnetic interaction with a near-field probe. We find localized states which are not observed in transmission and show that these states are shorter than the waveguide. We also directly obtain near-field measurements of the participation ratio, from which the size of the states can be derived, in quantitative agreement with the size measured with the perturbation method. 
Marko Spasenovic, Daryl M. Beggs, Philippe Lalanne, Thomas F. Krauss,   L. (Kobus) Kuipers
physics.optics