Wavefront Shaping of Plasmonic Beams by Selective Coupling

Custom plasmonic beams are advantageous for numerous scientific and technological aspects. While plasmonic wavefront shaping had traditionally been a truly planar process, taking place on a single surface, here we explore a new method for plasmonic shaping by selectively coupling plasmonic waves between different surfaces of an insulator–metal–insulator structure. In contrast to most previous shaping techniques that rely on free-space illumination, here the plasmonic beam in the buried surface acts as the light source. We demonstrate, both experimentally and numerically, a way to tailor the amplitude and phase of the wavefront using this new technique. The proposed method can be used to efficiently shape the plasmonic beam, for potential applications in sensing, interferometry, and communications.