Creation of tunable multiple 3D dark spots with cylindrical vector beam

Abstract

We present a method to generate multiple three-dimensional (3D) dark focal spots along the optical axis by focusing a cylindrical vector beam. The formation of uniform 3D dark spots is determined by optimizing three parameters of the pupil filter in the wavefront of the lens and the polarized state of the incident cylindrical vector beam. By adjusting the three parameters of the pupil filter, the number and position of dark spots can be controlled willingly, and the uniformity of dark spots can be adjusted by modulating the polarized state of the incident cylindrical vector beam. A single dark spot with uniform surrounding intensity is formed and double dark spots are also obtained with the proper parameters and can be separated with an equal distance away from the geometric focus. Moreover, multiple dark spots numbering up to six are formed along the optical axis. The size of each 3D dark spot is almost the same, and the central light intensity of the dark spots is nearly zero while the light intensity surrounding around is almost uniform. This work may find valuable application in particle trapping, microscopes, optical engineering, and so on.

Coherent-hybrid STED: high contrast sub-diffraction imaging using a bi-vortex depletion beam

“…To test the concept, we aimed at defining a phase-only mask that generates a hollow depletion beam featuring a dilation at the focal plane. A comprehensive resource for hollow beam engineering [25–29] is the field of optical trapping, where these beams find application in manipulating low-refractive index particles. However, in optical trapping the absolute intensity-zero is less important than sophistication of the dielectric maps (e.g.…”

Optical trapping with structured light: a review

“…161 The addition of DOEs such as SLMs at the input plane allows for the generation of exotic beam shapes, such as chains of light fields containing 3D dark volumes (low intensity spots) along the light field distributions. 162,163 Precise control over the beam shape to create a perfect spherical spot can be achieved using counterpropagating vector beams, which are constructively interfering at the common focal plane. [164][165][166] In this configuration, radially polarized vector beams can produce the spherical focal spot containing solely longitudinal electric fields, in contrast to the use of azimuthally polarized vector beams, which only contain the transverse components in the electric field.…”

Arbitrary cylindrical vector beam generation enabled by polarization-selective Gouy phase shifter

“…Under tight focusing [8][9][10], radial polarization possesses a sharper focal spot than a homogeneously polarized beam [11,12], while azimuthal polarization can be focused into a hollow spot [13]. These peculiar properties are useful for many applications such as particle manipulation [14][15][16][17][18], microscopy [19][20][21], material processing [22][23][24], near-field optics [25], and nonlinear optics [26]. Recently, the degrees of freedom of CVB are extended by ray-like trajectories [27], so that CVB also presents growing potentials in the area of optical encoding [28] and optical communications [29][30][31][32].…”