Monolayer semiconductor superlattices as hyperbolic materials at visible to near-infrared frequencies

Hyperbolic materials are natural or engineered artificial structures that provide means to manipulate and control electromagnetic radiation, leading to a variety of strong light-matter interactions at the nanoscale. In this work, we explore the physical properties of the optical response of two-dimensional (2D) semiconductor-based superlattices, which are engineered with atomic precision and composed of alternating 2D semiconductor monolayers and hexagonal-boron-nitride. We find that such superlattices exhibit a robust hyperbolic response at the visible to near-infrared spectrum, and with dimensions that are an order of magnitude smaller compared to conventional metal-based hyperbolic metamaterials, down to three active monolayers. By employing both analytical and numerical studies, we show that by varying the superlattice configuration we can control and manipulate the nature of the hyperbolic response. Finaly, we propose an optimal structure that will enable the experimental observation of this hyperbolic response in 2D semiconductors superlattices. Such highly compact hyperbolic materials of atomic precision could open the way for deep-subwavelength optoelectronic devices with an extremely small footprint.