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arXiv · 2212.09411

Optically enhanced second harmonic generation in silicon oxynitride thin films via local layer heating

Jakub Lukeš·Vít Kanclíř·Jan Václavík·Radek Melich·Ulrike Fuchs·Karel Žídek
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Abstract

Strong second harmonic generation (SHG) in silicon nitride has been extensively studied-among others, in terms of laser-induced SHG enhancement in Si3N4 waveguides. This enhancement has been ascribed to the all-optical poling induced by the coherent photogalvanic effect. Yet, an analogous process for Si3N4 thin films has not been reported. Our article reports on the observation of laser-induced 3-fold SHG enhancement in Si3N4 thin films. The observed enhancement has many features similar to all-optical poling, such as highly nonlinear power dependence, cumulative effect, or connection to the Si3N4-Si interface. However, identical experiments for low-oxygen silicon oxynitride thin films lead to complex behavior, including laser-induced SHG reduction. By a thorough experimental study, the observed results were ascribed to heat-induced SHG variation caused by multiphoton absorption. Such behavior indicates that the origin of optically-induced SHG enhancement in SiOxNy-Si structures can be a complex interplay of various phenomena.

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Jakub Lukeš, Vít Kanclíř, Jan Václavík, Radek Melich, Ulrike Fuchs, Karel Žídek. 2022-12-19. Optically enhanced second harmonic generation in silicon oxynitride thin films via local layer heating. https://arxiv.org/abs/2212.09411

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