Optical corral using a standing-wave Bessel beam

Abstract

Here we create a series of optical corrals and calculate their potential energy profile. A standing-wave Bessel beam is used to form traps in 1D (along the optical axis) and corrals in 2D, in planes perpendicular to the optical axis at the antinodal regions of the standing waves. These optical corrals are formed by an axicon-generated Bessel beam that is retro-reflected back onto itself. We report on Mie calculations of the 2D optical corrals and then compare the resulting probability distributions to those observed for latex particles of diameters 100, 200, and 300 nm. The experimental radial probability density function of tracked particles closely mimics the theoretical optical structure of a Bessel standing-wave corral. The Bessel standing-wave corrals we have characterized are being developed to measure rotational diffusion and torques on micro- and nanorods to help understand microfluidic behavior. The maximum forces on our small beads in the diffraction-free central zone of the Bessel beam standing wave are F||=0.5 pN and F⊥=0.1 pN.