Broadband near-infrared hyperbolic polaritons in MoOCl2

Hyperbolic polaritons have drawn great attention in nanoscale light manipulation due to their unique properties. Currently, most studies focus on natural hyperbolic phonon materials in the mid-infrared, limiting their application in the visible to near-infrared range. Here, we present a work on broadband near-infrared hyperbolic plasmon polaritons in a van der Waals material MoOCl2 by a perturbation-free direct imaging technique of photoemission electron microscopy. In particular, the hyperbolic polariton behavior has been dynamically tailored and manipulated by wavelength, polarization, interlayer twist, and artificial structure, providing a reconfigurable platform for nanophotonic applications. Notably, the full iso-frequency contours can be reconstructed via polarization-selective excitations. Our work has contributed to hyperbolic materials in the broadband near-infrared with MoOCl2, and has revealed PEEM to be an ideal method for studying hyperbolic plasmon polaritons at the space-time limit.