Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 82: Plasmonics and Nanooptics: Fabrication, Characterization and Applications II
O 82.4: Vortrag
Donnerstag, 20. März 2025, 11:15–11:30, H8
Strong polarization-tuned optical nonlinearity via femtosecond-laser plasmonic nanolithography in lithium niobate — •Han Zhu1,2, Shengqiang Zhou1, and Feng Chen2 — 1Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany — 2Shandong University, Jinan 250100, China
Despite the advantages of lithium niobate (LN)-based photonic integration platforms in various applications, the inherently weak third-order nonlinear optical response of conventional materials limits the miniaturization and energy efficiency of nonlinear optical devices in compact optical systems. Localized surface plasmons (LSPs) provide a promising solution to this miniaturization challenge by confining and enhancing light fields at deep subwavelength scales. However, due to nanofabrication limitations, strongly coupled single-crystal LN-LSP structures have yet to be realized. Here, we demonstrate Au nanorod-LN hybrid plasmonic structures assembled via plasmonic nanolithography. By leveraging plasmon-mediated energy deposition and photon momentum transfer under femtosecond laser irradiation, the nanoparticles within the single-crystalline region are formed from implanted elements. With plasmons excited in distinct axial directions, the resulting nanorod-LN hybrid plasmonic material exhibits polarization-dependent nonlinearity, with the nonlinear absorption coefficient for long-axis polarized light augmented by five orders of magnitude compared to the pure LN. Utilizing this feature, we develop a Q-switched laser exhibiting pronounced polarization-dependent behavior.
Keywords: Femtosecond-laser plasmonic nanolithography; Polarization-dependent optical nonlinearity; Lithium niobate crystal; Hybrid plasmonic materials; Saturable absorbers