Wednesday June 29, 2005
2 PM - 3:30 PM
ENG Z-50 Auditorium

Office Hours:
Friday July 1, 2005
3:30 PM - 4:30 PM
ENG 208

"Phonon-photonics - Infrared nanooptics based on surface phonon polaritons"
Dr. Rainer Hillenbrand
University of Technology Dresden

Surface polaritons (SPs) are electromagnetic surface waves propagating along the interface between two materials of negative and positive dielectric function, respectively. They allow fascinating micro- and nano-photonic applications in the fields of optical adressing, data storage or biosensing, mainly demonstrated for surface plasmon polaritons at visible and near-infrared frequencies. Surface phonon polaritons - electromagnetic surface modes formed by a strong coupling of infrared light and optical phonons in polar crystals - have hitherto attracted much less interest than surface plasmon polaritons although they can be excited on a wide range of insulators, semiconductors or ferroelectrics. The different material properties they offer could be applied for novel photonic applications. In this lecture the concept of phonon-photonics is introduced. This infrared nanotechnology exploits surface phonon polaritons in subwavelength-scale structures for confining, guiding and controlling infrared light. In an initial step we succeded in subwavelength-scale tailoring of the phononic properties of a SiC crystal. The structures we fabricated could be used as long-term near-field infrared read-out memories or for controlling electromagnetic energy transport by surface phonon polaritons in future nanoscale devices operating at infrared or terahertz frequencies. Further we demonstrate that the near-field interaction between a near-field probing tip and a polar crystal can be strongly enhanced due to tip-induced phonon-polariton resonance in the sample. Such phonon-enhanced near-field interaction is not only sensitive to the local chemical composition but also to the local structural properties of a sample. Besides chemical microscopy it thus allows to map crystal quality, lattice defects, polytypism or crystal orientation at nanoscale resolution. Altogether we envisage applications in optical nanospectroscopy and imaging of physical, chemical and biological nanocomposites.