Laboratory of 2D Materials & Nanodevices

Van der Waals bulk materials represent a unique class of materials composed of layers held together by weak van der Waals forces. These materials are of particular interest because individual monolayers can be isolated from them, exhibiting extraordinary physical and chemical properties. The most well-known examples include graphite, from which graphene can be obtained, and molybdenum disulfide (MoS₂), from which a monolayer of MoS₂ can be extracted. Hundreds of such materials have already been synthesized, while thousands of similar stable compounds have been predicted. Distinctive features of van der Waals materials include: The ability to exfoliate monolayers using mechanical or chemical methods; Significant anisotropy of properties, meaning their characteristics can vary greatly depending on the measurement direction (e.g., thermal and electrical conductivity can be much higher in-plane compared to out-of-plane); High chemical stability, making them attractive for various applications, including electronics and photonics; Unusual optical properties; The possibility of combining these materials to create functional homo- and heterostructures, as well as artificial materials with tailored properties. This project focuses on studying the optical properties of bulk van der Waals materials using spectroscopic ellipsometry and scattering-type scanning near-field optical microscopy (s-SNOM), as well as creating functional homo- and heterostructures with a designed optical response. Modern nanophotonics utilizes numerous novel phenomena for efficient light manipulation, such as bound states in the continuum (BIC), localized states in the continuum, chiral optical structures, and others. A key parameter for maximizing these effects is the refractive index, as it determines the resonant wavelength and quality factor (Q-factor). In most cases, even a slight increase in the refractive index provides a significant advantage in optical applications. However, conventional materials face fundamental limitations in their refractive index, whereas van der Waals materials overcome some of these constraints due to weak interlayer van der Waals bonding. This results in high in-plane refractive indices and strong optical anisotropy simultaneously. Thanks to their high refractive index and strong optical anisotropy, new possibilities emerge for light control at the nanoscale: Subwavelength optical interconnects (down to 100 nm) with high integration density for on-chip nanophotonics (post-silicon integrated nanophotonics); Directional propagation and sub-diffraction-limited focusing of polaritons; Realization of optical systems supporting Dyakonov surface waves, among others. The lack of data on the optical properties of van der Waals materials significantly hinders researchers and engineers in designing new photonic and optoelectronic devices based on these effects. The experimental data obtained in this project will allow for a detailed and precise description of bulk van der Waals materials and optical systems based on them. The optical properties of the studied materials will be published in open-access databases, making them available to all researchers. This project will contribute to the development of new technologies enabling the creation of artificial optical systems from tailored material combinations, promising for next-generation photonic and optoelectronic components. Research in this field is just beginning, and new discoveries may lead to even more efficient and functional materials.