Babicheva Viktoriia E, Chang Chun-Chieh
Department of Electrical and Computer Engineering, University of New Mexico, MSC01 1100, 1 University of New Mexico, Albuquerque, New Mexico 87131, United States.
Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
ACS Omega. 2025 Jun 2;10(22):23150-23160. doi: 10.1021/acsomega.5c01391. eCollection 2025 Jun 10.
Metasurfaces enable the generation of strong nonlinear signals, with nanoantenna resonances significantly enhancing the nonlinear response through tailored light-matter interactions. Commonly used nonlinear materials, such as lithium niobate and other similar crystals, have relatively moderate refractive indices, limiting their ability to achieve the strong mode localization attainable with high-refractive-index materials like silicon. Here, we report on enhancing mode confinement in nonlinear metasurfaces by employing conformal coatings of titania with atomic layer deposition (ALD). We develop a low-temperature ALD that enables the augmentation of resonances in materials that cannot withstand high-temperature processing, including polymers. We report on the design of a metasurface incorporating a nonlinear crystal and an ALD coating, achieving enhanced mode localization through this approach in the near-infrared wavelength range. We numerically demonstrate a significant enhancement in second-harmonic generation in the designed metasurface, achieved by optimizing the thickness of the ALD coating for the telecommunication wavelength.
超表面能够产生强非线性信号，纳米天线共振通过定制的光与物质相互作用显著增强非线性响应。常用的非线性材料，如铌酸锂和其他类似晶体，具有相对适中的折射率，限制了它们实现像硅等高折射率材料所能达到的强模式局域化的能力。在此，我们报告通过采用原子层沉积（ALD）的二氧化钛保形涂层来增强非线性超表面中的模式限制。我们开发了一种低温ALD工艺，该工艺能够增强那些无法承受高温处理的材料（包括聚合物）中的共振。我们报告了一种结合非线性晶体和ALD涂层的超表面的设计，通过这种方法在近红外波长范围内实现了增强的模式局域化。我们通过数值模拟证明，通过优化用于电信波长的ALD涂层厚度，在设计的超表面中二次谐波产生有显著增强。
