Ultra-strong nonlinear optical processes and trigonal warping in MoS2 layers

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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2017-12-01

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en

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Nature Communications, Volume 8, issue 1

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Nonlinear optical processes, such as harmonic generation, are of great interest for various applications, e.g., microscopy, therapy, and frequency conversion. However, high-order harmonic conversion is typically much less efficient than low-order, due to the weak intrinsic response of the higher-order nonlinear processes. Here we report ultra-strong optical nonlinearities in monolayer MoS2 (1L-MoS2): the third harmonic is 30 times stronger than the second, and the fourth is comparable to the second. The third harmonic generation efficiency for 1L-MoS2 is approximately three times higher than that for graphene, which was reported to have a large χ (3). We explain this by calculating the nonlinear response functions of 1L-MoS2 with a continuum-model Hamiltonian and quantum mechanical diagrammatic perturbation theory, highlighting the role of trigonal warping. A similar effect is expected in all other transition-metal dichalcogenides. Our results pave the way for efficient harmonic generation based on layered materials for applications such as microscopy and imaging.

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Säynätjoki, A, Karvonen, L, Rostami, H, Autere, A, Mehravar, S, Lombardo, A, Norwood, R A, Hasan, T, Peyghambarian, N, Lipsanen, H, Kieu, K, Ferrari, A C, Polini, M & Sun, Z 2017, ' Ultra-strong nonlinear optical processes and trigonal warping in MoS 2 layers ', Nature Communications, vol. 8, no. 1, 893 . https://doi.org/10.1038/s41467-017-00749-4