Demonstration of artificial nanostructures that convert light into surface waves traveling in one direction

Nano-optical control based on the theory of topological insulators

We have demonstrated nano-optical devices with diode-like rectifying action, which is essential for freely manipulating the propagation of light.

The University has also issued a press release.

Abstract

Valley polarization has recently been adopted in optics, offering robust waveguiding and angular momentum sorting. The success of valley systems in photonic crystals suggests a plasmonic counterpart that can merge topological photonics and topological condensed matter systems, for instance, two-dimensional materials with the enhanced light–matter interaction. However, a valley plasmonic waveguide with a sufficient propagation distance in the near-infrared (NIR) or visible spectral range has so far not been realized due to ohmic loss inside the metal. Here, we employ gap surface plasmons for high index contrasting and realize a wide-bandgap valley plasmonic crystal, allowing waveguiding in the NIR–visible range. The edge mode with a propagation distance of 5.3 μm in the range of 1.31–1.36 eV is experimentally confirmed by visualizing the field distributions with a scanning transmission electron microscope cathodoluminescence technique, suggesting a practical platform for transferring angular momentum between photons and carriers in mesoscopic active devices.