Optical trapping in counter-propagating Bessel beams

Abstract

We present and analyse a method that uses an interference of counter-propagating Bessel beams for 3D confinement of high-index micro-particles in array of optical traps. Due to this interference a sort of standing wave (SW) is created with intensity maxima separated by more than half a wavelength of the trapping beam and arranged along propagation axis. Thanks to the non-diffracting nature of this beam the region of SW existence is much longer comparing to the Gaussian beam of the similar beam diameter. Steep axial optical intensity gradients cause axial optical force that enables 3D particle confinement. Moreover, the self-healing property of Bessel beam suppresses the beam modification due to the presence of confined objects.