Optical tweezers and optical spanners with Laguerre–Gaussian modes

作者：N. B. Simpson, L. Allen, Miles J. Padgett · 发表于：Journal of Modern Optics · 年份：1996 · DOI：10.1080/09500349608230675 · 被引用次数：280 · 研究领域：Orbital Angular Momentum in Optics、Microfluidic and Bio-sensing Technologies、Near-Field Optical Microscopy

We numerically model the axial trapping forces within optical tweezers arising from Laguerre–Gaussian laser modes. For an 8 μm diameter sphere suspended in water, the higher-order modes produce an axial trapping force several times larger than that of the fundamental. Partial absorption results in a transfer of the orbital angular momentum from the Laguerre–Gaussian mode to the trapped particle. This results in the rotation of the particle by what may be called an optical spanner (wrench). For an absorption coefficient of α = 5700 m−1 and a laser power of 10 mW, we find that an 8 μm diameter sphere would acquire an angular acceleration of 10 × 104 rad s−2 and a limiting angular velocity of 0.2 rad s−1.