Angular momentum properties of hybrid cylindrical vector vortex beams in tightly focused optical systems

Abstract

Optical angular momenta (AM) have attracted tremendous research interest in recent years. In this paper we theoretically investigate the electromagnetic field and angular momentum properties of tightly focused arbitrary cylindrical vortex vector (CVV) input beams. An absorptive particle is placed in focused CVV fields to analyze the optical torques. The spin-orbit motions of the particle can be predicted and controlled when the influences of different parameters, such as the topological charge, the polarization and the initial phases, are taken into account. These findings will be helpful in optical beam shaping, optical spin-orbit interaction and practical optical manipulation.

Orbital Energy and Spin Flows in a Strong Focus of Laser Light

“…For the light field (26) in the focal plane (z=0), the on-axis projections of the Poynting vector, the orbital energy and spin flows take the form: [28,29] is generated because the on-axis projection of the spin flow is negative and larger in magnitude than the positive on-axis projection of the vector of the orbital energy flow. Because of this, contrary to the previously expressed guess, a dielectric microparticle put in the region of the reverse flow will not move in the negative direction [42].…”

“…5). When such a particle is located on the optical axis with its long axis lying in the focal plane, it is rotated around the center of mass and around the optical axis by the orbital energy flow P o,φ (21) or, in other words, by the longitudinal OAM component L z (24), similarly to rotation of particles along a circular trajectory in [11,26]. Since the effective refractive indices of an ellipsoidaltype particle differ for orthogonal polarizations directed along the long and short axes of the quasi-ellipse (birefringence), it is also rotated around the center of mass by the longitudinal SAM component S z (22) or, in other words, by the azimuthal spin flow P s,φ (16), similarly to rotation of crystalline birefringent particles in [38].…”

“…In [25], levitation of low-loss fused quartz spheres in vacuum was demonstrated. The rotation of dielectric microparticles along a circular path in focused laser beams has been studied [11,26]. In [12], rotation of an absorbing asymmetric microparticle around its center of mass was observed, but the particle was located in the side lobe of the diffraction pattern.…”

The Effect of the Spin Angular Momentum on the Tight‐Focusing Vortex Hollow Gaussian Beams

“…[ 17 ] In the tight focal fields carrying effective SAM, the absorptive particle is confined to a hot‐spot position of maximal optical torque. [ 20 ] Moreover, photons with certain OAM also show great potential in quantum information transmission, [ 21 ] optical quantum computation, [ 22 ] and encrypted quantum communication. [ 23 ] The topological charge carried by a vortex beam is a relatively stable parameter, and it is expected to be a carrier of information in optical communication.…”

Transformation of a vortex polarized beam in an anisotropic medium

“…In present time, there is growing interest in cylindrical vector vortex beams. This is due to the intensive development of high-tech applications: optical manipulation [1], laser technologies of nanomaterials [2], optical biosensors [3], high beam focusing [4], and optical communication [5]. To implement new applications, it is important to be able to control the properties of the beam, the papers [6] and [7] are devoted to the study of the spatial distribution and polarization of the beam.…”