Modelagem de nanoantenas ópticas como lançadores polaritônicos otimizados para dispositivos nanofotônicos

Author(s)

Rafael Alves Mayer

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin
• Defense date: 2021-02-26

Examining board members

Raul de Oliveira Freitas; Odilon Divino Damasceno Couto Junior; Christiano José Santiago de Matos

• Advisor: Christoph Friedrich Deneke; Raul de Oliveira Freitas

Abstract

Two-dimensional materials (2Ds) represent one of the greatest advances in materials science and engineering in the last decade. Currently, it is possible to find specific 2D options for each technological application, given that a vast catalog of these materials comprises ultrathin semiconductors with various "band gaps" (transition metal dichalcogenides), atomic semimetals (graphene), and flat insulators (hexagonal boron nitride) - hBN), among others. In the field of nanophotonics, 2Ds have been widely explored as they present hybrid modes of light and matter resonance that can be confined beyond the diffraction limit. Such modes, called polaritons, can be used in 2D heterostructures enabling the construction of, for example, highly compact optical modulators and photodetectors for mid-infrared to Terahertz ranges. To create such devices, current studies are based on numerical simulations that, despite their accuracy, they assume polariton sources that are impractical from the construction point of view. A strategy to address this problem is the use of optical antennas (OA), structures that convert light in the near field with high efficiency, as sources of polaritons in 2Ds. In this dissertation, we use the finite difference time domain (FDTD) simulation method to investigate the launch of HPhP in hBN by OA. Borrowing concepts from the theory of radio frequency antennas, such as field regions, radiation pattern, and directivity, we characterize the HPhP launching properties of OAs. We also demonstrate a highly directional launching of polaritons caused by dark plasmonic modes in OAs. Moreover, we investigate the nano-optical properties of 2D materials in different configurations. Among them, we study the acceleration of hyperbolic phonon polarities (HPhP) in hBN and Fabry-Perot cavity modes of HPhPs in MoO3 and SnO2 nanobelts. We additionally utilize experimental data from near-field scattered optical microscopy (s-SNOM) in the infrared to compare with simulation results. (AU)

• FAPESP's process: 19/08818-9 - Modulation of polaritons amplitude by two-dimensional dielectric junctions in the light of synchrotron infrared nanospectroscopy
• Grantee: Rafael Alves Mayer
• Support Opportunities: Scholarships in Brazil - Master