Tractor beams for optical micromanipulation

摘要

Tractor beams are traveling waves that transport illuminated objects in the retrograde direction relative to the direction of propagation. The theory of photokinetic effects identifies design criteria for long-range general-purpose tractor beams. These criteria distinguish first-order tractor beams that couple to induced dipole moments from higher-order tractor beams that rely on coupling to higher-order multipole moments to achieve pulling. First-order tractor beams are inherently longer-ranged and operate on a wider variety of materials. We explore the physics of first-order tractor beams in the context of a family of generalized solenoidal waves.