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arXiv · 2008.02403

Second-Harmonic Young Interference in Atom-Thin Heterocrystals

Wontaek Kim·Je Yhoung Ahn·Juseung Oh·Ji Hoon Shim·Sunmin Ryu
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Abstract

Optical second-harmonic generation (SHG) is a nonlinear parametric process that doubles the frequency of incoming light. Only allowed in non-centrosymmetric materials, it has been widely used in frequency modulation of lasers, surface scientific investigation, and label-free imaging in biological and medical sciences. Two-dimensional crystals are ideal SHG-materials not only for their strong light-matter interaction and atomic thickness defying the phase-matching requirement but also for their stackability into customized hetero-crystals with high angular precision and material diversity. Here we directly show that SHG in hetero-bilayers of transition metal dichalcogenides (TMDs) is governed by optical interference between two coherent SH fields with material-dependent phase delays using spectral phase interferometry. We also quantify the frequency-dependent phase difference between MoS2 and WS2, which also agrees with polarization-resolved data and first-principles calculations on complex susceptibility. The second-harmonic analogue of Young double-slit interference shown in this work demonstrates the potential of custom-designed parametric generation by atom-thick nonlinear optical materials.

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Wontaek Kim, Je Yhoung Ahn, Juseung Oh, Ji Hoon Shim, Sunmin Ryu. 2020-08-06. Second-Harmonic Young Interference in Atom-Thin Heterocrystals. https://doi.org/10.1021/acs.nanolett.0c03763

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