Webinars

Two-dimensional materials are at the core of many fields of modern optoelectronics [1] and nanophotonics [2]. However, relatively small research attention is devoted to their bulk counterparts [3,4]. In this webinar, we demonstrate that bulk van der Waals crystals (MoS2, WS2, MoSe2, WSe2, hBN, and many others) are even more promising material platforms for optical applications than two-dimensional materials thanks to unprecedented giant optical anisotropy (around 2) and high refractive index (around 4) in a broad spectral range from ultraviolet (for hBN) to visible (for MoS2 and WS2) and near-infrared (for MoSe2 and WSe2) wavelengths. These outstanding properties allow us to design next-generation integrated circuits and optical elements [4-7].

In detail, we managed to achieve unmatched lateral dimensions for van der Waals-based waveguides with only several tens of nanometers footprint. In other words, it gives a unique opportunity to place around 10000 waveguides on an mm-scale photonic chip. These characteristics make us a step closer to electronic integrated circuits. Hence, van der Waals-based photonic integrated circuits can become a decisive platform for an electronic-to-photonic replacement to increase computer data processing. The idea behind the use of van der Waals materials has four advantages. First, van der Waals crystals have larger optical bandgap in comparison with conventional high refractive index materials (TiO2, GaP, Si, Ge, and many others) and, therefore, smaller operation wavelength without dissipative losses [4]. Secondly, van der Waals materials have one of the largest refractive indices among known materials [4]. Thirdly, the record-breaking optical anisotropy of van der Waals gives an additional degree of freedom for the design optimization of integrated photonic elements [4]. Finally, van der Waals materials have dangling bonds-free surfaces and atomically sharp edges after the lithography process, which results in minimum scattering losses in photonic waveguides and high-intensity nonlinear properties in addition to superior linear response [7-9]. From a broader perspective, we would like to note that these van der Waals features are also beneficial for countless optical devices (resonators, dielectric mirrors, waveplates, and many others) beyond on-chip integration.