In his thesis, Yaraslau Tamashevich introduces two complementary approaches to studying light-matter interactions: a semiclassical model, where quantum systems interact with external fields via Schrödinger's equation, and a path integral formulation rooted in quantum mechanics, employing the principle of minimal action. Together, these methodologies provide robust tools for analyzing the optical properties of advanced materials.
In his research, Tamashevich explores the nonlinear light-matter interaction of different novel materials, such as graphene, Weyl materials and epsilon-near-zero (ENZ) materials.
By using an effective semiclassical model, the study explores the nonlinear interaction between structured light and graphene, a prominent Dirac material. It reveals that the high-harmonic generation process impacts orbital angular momentum (OAM) charge of the harmonics, with the nonlinear response carrying a multiple of the fundamental OAM charge.
"This discovery could enable the development of innovative optical devices utilising structured light", explains Yaraslau.
Another type of 2D materials that has been studied are Weyl materials.
Tamashevich investigates the unique optical properties of Weyl materials, highlighting distinct differences from graphene. Through detailed calculations, he demonstrates that the nonlinear optical response of these materials varies with polarization and is further tunable via magnetic fields, owing to the emergence of Landau levels.
Additionally, he presents a novel model for ENZ materials using path integrals to derive a nonperturbative expression for their permittivity. This approach moves beyond traditional nonlinear optics models, providing fresh insights into Kerr-like effects in ENZ media and offering potential benefits for ultrafast optics and metamaterials.
“This work offers new perspectives on the interaction between light and advanced materials, providing a framework that can drive innovation in both fundamental science and practical applications”, concludes Yaraslau Tamashevich.
Yaraslau Tamashevich is originally from Belarus and has been working as a researcher in the Theoretical Optics and Photonics (TOP) Group at Tampere University.
Public defence on Friday 7 March
The doctoral dissertation ofMSc (Tech) Yaraslau Tamashevich in the field of Physics titled Nonlinear Light-matter Interaction: from 2D to Nonperturbative Materials will be publicly examined at the Faculty of Engineering and Natural Sciences at Tampere University at 13 o’clock on Friday 7th of March 2025 at Hervanta campus, Festia building, auditorium Pieni sali 1 (Korkeakoulunkatu 8, Tampere).
The Opponent will be Professor Andrea Marini from University of L'Aquila. The Custos will be Associate Professor Marco Ornigotti from the Faculty of Engineering and Natural Sciences at Tampere University.