Propagation Characteristics of Circular Airy Vortex Beams in a Uniaxial Crystal along the Optical Axis

Abstract

Circular airy vortex beams (CAVBs) have attracted much attention due to their “abruptly autofocusing” effect, phase singularity, and their potential applications in optical micromanipulation, communication, etc. In this paper, we numerically investigated the propagation properties of circular airy beams (CABs) imposed with different optical vortices (OVs) along the optical axis of a uniaxial crystal for the first time. Like other common beams, a left-hand circular polarized (LHCP) CAVB, propagating along the optical axis in a uniaxial crystal, can excite a right-hand circular polarized (RHCP) component superimposed with an on-axis vortex of topological charge (TC) number of 2. When the incident beam is an LHCP CAB imposed with an on-axis vortex of TC number of l = 1, both of the two components have an axisymmetric intensity distribution during propagation and form hollow beams near the focal plane because of the phase singularity. The phase pattern shows that the LHCP component carries an on-axis vortex of TC number of l = 1, while the RHCP component carries an on-axis vortex of TC number of l = 3. With a larger TC number (l = 3), the RHCP component has a larger hollow region in the focal plane compared to the LHCP component. We also studied cases of CABs imposed with one and two off-axis OVs. The off-axis OV makes the CAVB’s profile remain asymmetric throughout the propagation. As the propagation distance increases, the off-axis OVs move near the center of the beam and overlap, resulting in a special intensity and phase distribution near the focal plane.

The Propagation Characteristics of Circular Airy Beams with Propagational Fractional-Order Optical Vortices

“…Deng D. M. et al found that the focal length and the intensity of the optical focus can be modified by appropriately selecting the distribution factor, the TC, and the size of the incident beams [36]. In 2022, we found that a left circularly polarized CAB imposed with an on-axis OV will give rise to both left and right circularly polarized components with OV in the crystal [38]. What is the influence of fractional-order OV on a CAB, and does the CAB retain its "non-diffracting", "self-healing", and "abruptly autofocusing" properties?…”

Generation of auto-focusing vortex beam via segment vortex phase for imaging edge-enhancement

“…During propagation, the CAB can initially keep a low-intensity distribution, then abruptly converge to a focal point where the intensity is suddenly enhanced by orders of magnitude [25][26][27][28][29]. In recent years, vortex phase modulation has allowed for the extension of the CABs from single vortex CABs to double or multiple vortex CABs [30][31][32][33][34]. Therefore, combining the CAB and the segmented vortex phase is of great interest to facilitate more flexible control of the auto-focusing characteristics and local vortex of the beam.…”

Properties of a Lorentz correlated beam in uniaxial crystal

“…The rectangular coherence source is proposed 8 . Now, the theory of beam in uniaxial crystal is produced, 9 and the effects of uniaxial crystal on properties of beams are widely investigated, such as sine and cosine beams, 10,11 Airy vortex beam, 12 cosh‐Gaussian beam, 13 vortex cosine‐hyperbolic‐Gaussian beam, 14 chirped sinh‐Gaussian beam, 15 rotating beam, 16 radially polarized LGSM beams, 17 MGSM vortex beams, 18 rectangular LGSM beam, 19 rectangular MGSM vortex beam, 20 and rectangular MGSM beam 21 . Recently, the Lorentz‐correlated Schell‐model (LCSM) beam with the cusped shape is introduced, 6 and the LCSMB is also extended to nonuniform LCSMB 22 .…”