Coherent control approaches to light guidance in the nanoscale

Concepts of coherent control are extended to manipulate light in subdiffraction length scales via nanoparticle arrays. Phase and polarization control are first introduced and applied to control the pathway of electromagnetic energy through multiple branching nanoarray intersections, leading to an ultrafast optical nanoswitch below the diffraction limit. The genetic algorithm is next generalized to provide a systematic design tool, wherein both the properties of the excitation field and the structural parameters of the material system are optimized so as to make nanodevices with desired functionality. The scheme is used to gain insight into the interplay between the interactions that underlies the coherent propagation of electromagnetic energy via nanoparticle arrays. Implications to several research fields, including single molecule spectroscopy, spatially confined chemistry, optical logic, and nanoscale sensing, are envisioned.