Optical Gradient Forces of Strongly Localized Fields

作者：Tsvi Tlusty, A. MELLER, Roy Bar‐Ziv · 发表于：Physical Review Letters · 年份：1998 · DOI：10.1103/physrevlett.81.1738 · 被引用次数：117 · 研究领域：Orbital Angular Momentum in Optics、Near-Field Optical Microscopy、Microfluidic and Bio-sensing Technologies

We present a new approach for determining optical gradient forces applied by strongly focused laser beams on dielectric particles. We show that when the electromagnetic field is focused to a diffraction limited spot a dipole approximation is valid for any particle size. We derive intuitive predictions for force-displacement curves, maximal trapping forces, and force constants. The theory fits well with recent measurements of particles trapped by laser tweezers. We also discuss effects of radiation pressure and gravity.