Hernández-Sarria J J, Oliveira Osvaldo N, Mejía-Salazar J R
Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13560-970, São Carlos, SP, Brasil.
Instituto Nacional de Telecomunicações (Inatel), 37540-000, Santa Rita do Sapucaí, MG, Brazil.
Phys Rev Lett. 2021 Oct 29;127(18):186803. doi: 10.1103/PhysRevLett.127.186803.
A challenge in plasmonic trapping of small nanoparticles is the heating due to the Joule effect of metallic components. This heating can be avoided with electromagnetic field confinement in high-refractive-index materials, but nanoparticle trapping is difficult because the electromagnetic fields are mostly confined inside the dielectric nanostructures. Herein, we present the design of an all-dielectric platform to capture small dielectric nanoparticles without heating the nanostructure. It consists of a Si nanodisk engineered to exhibit the second-order anapole mode at the infrared regime (λ=980 nm), where Si has negligible losses, with a slot at the center. A strong electromagnetic hot spot is created, thus allowing us to capture nanoparticles as small as 20 nm. The numerical calculations indicate that optical trapping in these all-dielectric nanostructures occurs without heating only in the infrared, since for visible wavelengths the heating levels are similar to those in plasmonic nanostructures.
小纳米颗粒的等离激元捕获面临的一个挑战是金属部件的焦耳效应导致的加热。通过在高折射率材料中进行电磁场限制可以避免这种加热，但纳米颗粒捕获很困难，因为电磁场大多被限制在介电纳米结构内部。在此，我们展示了一种全介电平台的设计，用于捕获小介电纳米颗粒而不加热纳米结构。它由一个硅纳米盘组成，该硅纳米盘经过设计，在红外波段（λ = 980 nm）表现出二阶无偶极模式，在该波段硅的损耗可忽略不计，并且在中心有一个狭缝。会产生一个强烈的电磁热点，从而使我们能够捕获小至20 nm的纳米颗粒。数值计算表明，这些全介电纳米结构中的光捕获仅在红外波段不产生加热，因为对于可见光波长，加热水平与等离激元纳米结构中的相似。
