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arXiv · 2403.19385

Even-order optical harmonics generated from centrosymmetric-material metasurfaces

Pavel Tonkaev·Fangxing Lai·Sergey Kruk·Qinghai Song·Michael Scalora·Kirill Koshelev·Yuri Kivshar
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Abstract

Generation of even-order optical harmonics requires noncentrosymmetric structures being conventionally observed in crystals lacking the center of inversion. In centrosymmetric systems, even-order harmonics may arise, e.g., at surfaces but such effects are usually very weak. Here we observe optical harmonics up to 4-th order generated under the normal incidence from centrosymmetric dielectric metasurfaces empowered by resonances. We design silicon metasurfaces supporting optical quasibound states in the continuum and guided-mode resonances, and demonstrate the enhancement of second-harmonic signals by over three orders of magnitude compared to nonresonant thin films. Under the optimal conditions, the brightness of the second harmonic approaches that of the third harmonic, and the 4th-order harmonic becomes detectable.

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Pavel Tonkaev, Fangxing Lai, Sergey Kruk, Qinghai Song, Michael Scalora, Kirill Koshelev, Yuri Kivshar. 2024-03-28. Even-order optical harmonics generated from centrosymmetric-material metasurfaces. https://arxiv.org/abs/2403.19385

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