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arXiv · 2511.15451

Thickness-dependence of Linear and Nonlinear Optical Properties of Multilayer 3R-MoS2

Fatemeh Abtahi·Alen Shaji·Gia Quyet Ngo·Benjamin Laudert·Hossein Esfandiar·Sebastian W. Schmitt·Falk Eilenberger
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Abstract

3R-MoS2, a MoS2 polytype with broken inversion symmetry, enables unique light-matter interactions and is promising for linear and nonlinear integrated photonics beyond the monolayer limit. Yet, systematic studies of its thickness-dependent reflectivity and its impact on harmonic generation are still lacking. . Yet, systematic studies of its thickness-dependent reflectivity and its impact on harmonic generation are still lacking. Here, we introduce a non-destructive optical method to determine the thickness of 3r-MoS2 flakes from reflectivity measurements, offering AFM-like precision with a mean bias of less than 2 nm range, while being much faster and applicable to non-solid substrates such as PDMS, in the 3-200 nm range. Nonlinear characterization further reveals distinct thickness-dependent maxima in second- and third-harmonic generation (SHG/THG), with the first clear peak at ~200 nm. These maxima arise from Fabry-P\'erot-type phase matching conditions mediated by the film thickness and can further be shaped by absorption. This work thus provides both a practical thickness metrology and new insights for exploiting thickness-dependent 3R-MoS2 nonlinearities in scalable photonic technologies.

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Fatemeh Abtahi, Alen Shaji, Gia Quyet Ngo, Benjamin Laudert, Hossein Esfandiar, Sebastian W. Schmitt, Falk Eilenberger. 2025-11-19. Thickness-dependence of Linear and Nonlinear Optical Properties of Multilayer 3R-MoS2. https://arxiv.org/abs/2511.15451

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