Manipulating Hyperbolic Plasmon Polaritons at Near-Infrared in an Anisotropic van der Waals Crystal

Controlling nanoscale light propagation via novel materials and phenomena is at the core of nanophotonics. Hyperbolic polaritons in anisotropic materials offer extreme field confinement and directional propagation. However, most of the studies are concentrated in mid-infrared, limiting their potential for future nanophotonics and quantum devices. Here, we study the manipulation of near-infrared low-loss hyperbolic plasmon polaritons in van der Waals material MoOCl₂ by using light field as the control parameter through photoemission electron microscopy. Both the oblique incidence direction and the polarization can serve as independent degrees for dynamic control in the near-infrared range. Our method presents that through the configuration of the light source to break the intrinsic symmetry, hyperbolic polariton modes can be achieved in a desired way. This study confirms that near-infrared hyperbolic polaritons can be effectively achieved and tuned, providing an exotic platform for on-chip applications.