Atomic-Void van der Waals Channel Waveguides

Abstract: Layered van der Waals materials offer a unique platform for creating atomic-void channels with sub-nanometer dimensions. Coupling light into these channels may further advance sensing, quantum information, and single molecule chemistries. Here we examine limits of light guiding in atomic-void channels and show that van der Waals materials exhibiting strong resonances - excitonic and polaritonic - are ideally suited for deeply subwavelength light guiding. We demonstrate that excitonic transition metal dichalcogenides can squeeze > 70% of optical power in just < {\lambda}/100 thick channel in the visible and near-infrared. We also show that polariton resonances of hexagonal boron nitride allow deeply subwavelength (< {\lambda}/500) guiding in the mid-infrared. We further reveal effects of natural material anisotropy and discuss the influence of losses. Our analysis shows van der Waals channel waveguides while offering extreme optical confinement exhibit significantly lower loss compared to plasmonic counterparts. Such atomic void waveguides pave the way to low loss and deeply subwavelength optics.