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arXiv · 2301.08089

Enhanced Surface Second Harmonic Generation in Nanolaminates

Fatemeh Abtahi·Pallabi Paul·Sebastian Beer·Athira Kuppadakkath·Anton Pakhomov·Adriana Szeghalmi·Stefan Nolte·Frank Setzpfandt·Falk Eilenberger
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Abstract

Second-harmonic generation (SHG) is a second-order nonlinear optical process that is not allowed in media with inversion sym-metry. However, due to the broken symmetry at the surface, surface SHG still occurs, but is generally small. We experimentally investi-gate the surface SHG in periodic stacks of alternating, subwave-length dielectric layers, which have a large number of surfaces, thus enhancing surface SHG considerably. To this end, multilayer stacks of SiO2/TiO2 were grown by Plasma Enhanced Atomic Layer Deposition (PEALD) on fused silica substrates. With this technique individual layers of a thickness of less than 2 nm can be fabricated. We experimentally show that under large angles of incidence (> 20 degrees) there is substantial SHG, well beyond the level, which can be observed from simple interfaces. We perform this experiment for samples with different periods and thickness of SiO2/TiO2 and our results are in agreement with theoretical calculations.

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Fatemeh Abtahi, Pallabi Paul, Sebastian Beer, Athira Kuppadakkath, Anton Pakhomov, Adriana Szeghalmi, Stefan Nolte, Frank Setzpfandt, Falk Eilenberger. 2023-01-19. Enhanced Surface Second Harmonic Generation in Nanolaminates. https://doi.org/10.1364/oe.484893

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