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HL: Fachverband Halbleiterphysik
HL 54: 2D Materials IX – Photonic properties and devices
HL 54.3: Vortrag
Freitag, 13. März 2026, 10:00–10:15, POT/0081
Analytical Theory Of Third Harmonic Generation In Two-Dimensional Materials — •Shridhar Sanjay Shanbhag1, Florentine Friedrich2, Paul Herrmann2, Sebastian Klimmer2, Giancarlo Soavi2, and Jan Wilhelm1 — 1Institute of Theoretical Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93053 Regensburg, Germany — 2Institute of Solid State Physics, Friedrich Schiller University Jena, 07743 Jena, Germany
Valleytronics explores the valley degree of freedom in materials like transition metal dichalcogenides (TMDs), using electrons in ±K valleys as binary states for information encoding. In valleytronics applications, efficient valley readout is crucial. We show that third harmonic generation (THG) provides an ultrafast solution to valley readout for both centrosymmetric and non-centrosymmetric materials [1].
We solved the semiconductor Bloch equations perturbatively to derive an analytical expression for the polarization state of the emitted third harmonic signal. Our analysis shows how material parameters influence the polarization and attributes polarization rotation to spin and valley dependent optical Stark and Bloch-Siegert shifts in TMDs. Our theoretical predictions closely align with experiments, providing the microscopic mechanism and thus helping advance valleytronic readout mechanisms.
[1] Friedrich, F., Herrmann, P., Shanbhag, S.S. et al. Nat. Photon. (2025). https://doi.org/10.1038/s41566-025-01801-2
Keywords: TMD; Valleytronics; nonlinear; ultrafast; THG