高阶结构光定制多极光镊捕获

中文摘要 AI 辅助

偶极光力可以将瑞利尺寸的介电粒子限制在强度极大值或极小值附近，这通常被称为亮捕获和暗捕获。结构光照明为定制捕获景观开辟了机会，揭示了灰捕获的可能性，特别是对于能够激发高阶多极响应的较大米氏粒子。虽然先前的研究主要集中在对一些示例性聚焦标量光束的梯度力计算上，我们不仅通过将矢量聚焦与广义洛伦兹-米氏理论相结合来扩展这些分析，而且还考虑了更复杂的捕获场。受其独特的紧聚焦行为、形成强横向强度梯度和三维电场分量的启发，我们探索了高阶柱对称标量和矢量光束。我们从理论上研究了米氏区域硅纳米球在水中的多极捕获，计算了三维净辐射力，并通过力雅可比矩阵评估了局部捕获稳定性。在八极米氏共振附近，我们预测了矢量光束的稳定灰捕获，且效率更高。此外，我们发现了能够实现可配置的、依赖于粒子尺寸的灰/暗捕获的场几何结构，且具有亚波长粒子间距。这些结果确立了偏振、照明结构和粒子参数作为半径依赖多极捕获的互补控制手段，为亚波长粒子分选、捕获辅助纳米图案化和光学束缚研究等潜在应用提供了基础。

英文摘要

Dipolar optical forces can confine Rayleigh-sized dielectric particles towards or away from intensity maxima, commonly known as bright and dark trapping. Structured light illumination opens up opportunities for customized trapping landscapes, unveiling the possibility of gray trapping, especially for larger Mie particles that can excite a higher-order multipolar response. While previous studies have primarily focused on calculations of the gradient force for some exemplary, focused scalar beams, we not only extend these analyses by combining vectorial focusing with generalized Lorenz-Mie theory, but also consider more complex trapping fields. Motivated by their unique tight focusing behavior, shaping strong transverse intensity gradients and three-dimensional electric field components, we explore higher-order cylindrical scalar and vector beams. We theoretically investigate multipolar trapping of Mie-regime silicon nanospheres in water, calculating the three-dimensional net radiation force and assess local trapping stability through the force Jacobian. Near an octupolar Mie resonance, we predict stable gray trapping with enhanced efficiency for vector beams. Further, we find field geometries enabling configurable, particle-size-dependent gray/dark trapping with subwavelength inter-particle spacing. These results establish polarization, illumination structure and particle parameters as complementary controls for radius-dependent multipolar trapping, providing a basis for potential applications in sub-wavelength particle sorting, trapping-assisted nanopatterning and optical binding investigations.

发表机构

• The Institute of Optics, University of Rochester（罗切斯特大学光学研究所）
• Department of Physics, University of Rochester（罗切斯特大学物理系）
• Center for Coherence and Quantum Optics, University of Rochester（罗切斯特大学相干与量子光学中心）

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