Dresden 2026 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 20: Poster I

HL 20.18: Poster

Dienstag, 10. März 2026, 18:00–20:00, P1

Nonlinear interference in a CrSBr BIC metasurface — •Fabian Glatz¹, Thomas Weber², Till Weickhardt¹, Luca Sortino², Andreas Tittl², and Giancarlo Soavi¹ — ¹Friedrich Schiller University Jena — ²Ludwig Maximilians University of Munich

The active electrical [1] and all-optical [2] modulation of the nonlinear optical (NLO) response of layered materials has attracted great interest for nanophotonic applications. Ferroic layered materials, such as CrSBr, offer an alternative and powerful approach for NLO tuning thanks to temperature-dependent phase transitions [3]. Here, we present a new method where NLO modulation arises from interference effects between bound states in the continuum (BIC) resonances and the bulk NLO susceptibility of a CrSBr nanophotonic device. To achieve this, we patterned exfoliated CrSBr flakes into metasurfaces that exhibit BICs and investigated their NLO response. By varying the dimensions of the metasurface, we obtain direct control over the energy, linewidth and Q-factor of the BIC resonances [4]. When the energy of the BIC resonance is close to that of the CrSBr exciton, we further observe a strong modulation in third harmonic generation (THG), characterized by both constructive and destructive interference depending on the energy of the emitted TH signal. These results allow us to retrieve the real and imaginary parts of the BIC-resonance, and they further demonstrate a new powerful approach for NLO engineering at the nanoscale. [1] Soavi et al. Nat. Nanotech. 13, (2018). [2] Klimmer et al. Nat. Photon. 15, (2021). [3] Wang et al. Nat. Com. 14, (2023). [4] Weber et al. Nat. Mater. 22, (2023).

Keywords: CrSBr; metasurface; nonlinear optics; bound states in the continuum