Recent advances in 2D materials synthesis have allowed the formation of few-atomic-layer group (III) metals through confinement heteroepitaxy (CHet). These emerging materials have great promise for nonlinear optical applications at NIR/Vis frequencies, with second-order nonlinear susceptibilities over 10 nm/V, an ~500x improvement over LiNiBO<sub>3</sub> and rivaling 2D chalcogenides. The 2D indium and gallium layers presented here support a visible plasmon resonance with a coherence time measured by nonlinear optical interferometry of ~20 fs. In this presentation, using the example of two-atomic-layer indium, I will demonstrate the use of polarization- and angle- resolved SHG microscopy to understand the underlying metal structure. The metal adopts the hexagonal structure of the SiC substrate. An evolution in bonding character across metal layers results in an axial dipole, enabling the second-order nonlinear response by out-of-plane symmetry breaking. The unprecedented NIR/VIS SHG from the 2D metals described here, along with their environmental stability and potential integration into heterostructures, demonstrate their potential for applications at telecommunication wavelengths.

Second harmonic generation in two-dimensional polar metals

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.