Focusing of surface phonon polaritons

A. J. Huber, B. Deutsch, L. Novotny, and R. Hillenbrand

Applied Physical Letters 92, p.203104 (2008)
Surface phonon polaritons (SPs) on crystal substrates have applications in microscopy, biosensing, and photonics. Here, we demonstrate focusing of SPs on a silicon carbide (SiC) crystal. A simple metal-film element is fabricated on the SiC sample in order to focus the surface waves. Pseudoheterodyne scanning near-field infrared microscopy is used to obtain amplitude and phase maps of the local fields verifying the enhanced amplitude in the focus. Simulations of this system are presented, based on a modified Huygens’ principle, which show good agreement with the experimental results.