Abruptly autofocused and rotated circular chirp Pearcey Gaussian vortex beams

Intensity controlled and multi-multiplexed full-space achromatic metalens and modulated orbital angular momentum

The Fabry-Perot (F-P) interference model was used to make a 6-layer metasurface with cross-polarization that can be changed by heat. The fundamental concept behind the metasurface is to utilize the selectivity of linearly polarized waves by a metal grating to achieve broadband and efficient polarized conversion (PC). It also uses the thermal conversion properties of vanadium dioxide (VO2) to control the amplitude of terahertz (THz) waves in a dynamic way. While achromatic metalenses have been extensively studied, altering the entire spatial incidence angle remains relatively uncommon. Enter modulated orbital angular momentum (MOAM), a promising approach for applications such as holographic encryption, optical communication, and imaging. However, achieving MOAM multidimensional multiplexing has proven to be a significant challenge. In response to this challenge, we have integrated the transmission phase into the metasurface design. This new idea makes it possible to make a full spatially achromatic metalenses with angular multiplexing and makes MOAM multidimensional multiplexing easier by letting you switch between frequency, angle, and MOAM modes. This pioneering approach unveils new prospects for enhancing the capacity, rate, and quality of information exchange in domains such as optical encryption, optical imaging, optical communication, and other related technological fields.

Nonparaxial propagation and the radiation forces of the chirped circular Airy derivative beams

In this paper, we investigate the nonparaxial propagation dynamics of the chirped circular Airy derivative beams (CCADBs) based on vector angular spectrum method. In the case of nonparaxial propagation, the CCADBs still maintains excellent autofocusing performances. Derivative order and chirp factor are two important physical quantities of the CCADBs to regulate the nonparaxial propagation characteristics, such as focal length, focal depth and K-value. In the nonparaxial propagation model, the radiation force on a Rayleigh microsphere induced the CCADBs are also analyzed and discussed in detail. The results demonstrate that not all derivative order CCADBs can achieve stable microsphere trapping effect. The derivative order and chirp factor of the beam can be used to coarse and fine tune the capture effect of Rayleigh microsphere, respectively. This work will contribute to the more precise and flexible use of circular Airy derivative beams in optical manipulation, biomedical treatment and so on.

Autofocusing field constructed by ring-arrayed Pearcey Gaussian chirp beams

In this work, we propose and demonstrate the ring-arrayed Pearcey Gaussian chirp beams (RAPGCBs) synthesized by multiple two-dimensional Pearcey beams. The general analytical formula for the propagation of RAPGCBs is presented. We find that, depending on synthesized number n, the profiles of the beams present different polygonal shapes, and the autofocusing properties can be controlled by chirp factor β. Furthermore, we study the properties of the RAPGCBs carrying optical vortices (OVs). It shows that a single OV or two positive OVs form an autofocusing hollow field, and opposite OVs will annihilate, which results in greatly increased autofocusing ability. Our experimental results agree with the simulations. Such beams have potential applications in particle trapping and biology medical fields.

Controllable focusing behavior of chirped Pearcey-Gaussian pulses under time-dependent potentials

We investigate the propagation dynamics of the Pearcey-Gaussian (PG) pulses in the presence of time-dependent potentials in a linear medium both theoretically and numerically. We demonstrate that the combination of the linear potential and the initial chirp of PG pulses can flexibly control the propagation trajectory and inherent focusing properties of the PG pulses. When the parabolic potential is taken into account, the chirped PG pulses are periodically focused and reversed. By adjusting the parabolic potential and the pulse chirp, the characteristics of the focal points, such as position, intensity, and spacing between focal points, can be manipulated effectively. The interaction of two temporally separated PG pulses still shows a periodic evolution with controllable focusing characteristics. These results can broaden the application range of PG pulses and provide some inspiration for the control of PG pulses under nonlinear conditions.

Abruptly autofocusing of generalized circular Airy derivative beams

In this paper, we introduce a novel kind of abrupt autofocusing beams namely the generalized circular Airy derivative beams (CADBs) as an extension of circular Airy beam (CAB). The propagation dynamics of the CADBs is examined theoretically. Our results show that the CADBs exhibit stronger autofocusing ability than the CAB under the same condition. The physical mechanism of the abruptly autofocusing of the CADBs is interpreted by mimicking the Fresnel zone plate lens. Here, the abruptly autofocusing ability is described by a ratio K = Ifm/I_0m where Ifm and I_0m correspond to the maximum intensities in the focal and the source planes, respectively. As an example, the K-value of the circular Airyprime beam (CAPB, the first-order Airy derivative beam) is about 7 times of that of the CAB. In addition, the CAPB have narrower FWHM (full width at half maxima) in the focus position than the CAB, and the focal spot size of the CAPB is smaller than that of the CAB. Furthermore, we establish an optical system involving a phase-only spatial light modulator to generate the CAPB and measure its autofocusing characteristics experimentally. The measured K-value is about 9.4 percentage error between theory and experiment owing to the imperfection generation of the CAPB. The proposed generalized CADBs will find applications in biomedical treatment, optical manipulation and so on.

Experimental generation of the polycyclic tornado circular swallowtail beam with self-healing and auto-focusing

In this paper, the polycyclic tornado circular swallowtail beam (PTCSB) with autofocusing and self-healing properties is generated numerically and experimentally and their properties are investigated. Compared with the circular swallowtail beam (CSB), the optical distribution of the PTCSB presents a tornado pattern during the propagation. The number of spiral stripes, as well as the orientation of the rotation, can be adjusted by the number and the sign of the topological charge. The Poynting vectors and the orbital angular momentum are employed to investigate the physical mechanism of beam-rotating. In addition, we also introduce a sector-shaped opaque obstacle to investigate the self-healing property of the PTCSB, passing through it with different center angles and discuss the influence of the scaling factor along the propagation direction. Our results may expand the potential applications in the optical spanner and material processing.

Multiple and off-axis optical bottles from the chirped circular Pearcey Gaussian vortex beams

We introduce a new type of multiple and off-axis optical bottles (OBs) based on the chirped circular Pearcey Gaussian vortex beam. This kind of beam allows the generation of the OBs with a perfect bottle shape through coherent superposition. Also, we show that the number and the position of the OBs can be precisely and flexibly controlled. The experimental results agree well with our numerical simulations, and we observe stable trapping of the mesocarbon microbeads particles by the proposed bottle beam.

Design of autofocusing beams based on accelerating beams

Autofocusing Airy-like beams have been designed based on the self-accelerating beams along arbitrary polynomial paths. The evolutions of the autofocusing beam in free space and turbulent atmosphere have been studied. Results show that the energy concentration of the autofocusing beam near the focal plane has a close relationship with its accelerating trajectory. The spot size of the autofocusing beam in the focal plane varies with the acceleration trajectory. The influence of turbulence on different autofocusing beams is different and has a relation with the degree of the curvature of the accelerating beam. The autofocusing beam propagating along a small curvature path has better resistance against turbulence.

Dual-focusing behavior of a one-dimensional quadratically chirped Pearcey-Gaussian beam

In this paper, we provide analytical solutions describing the dynamic behavior of the Pearcey-Gaussian beams propagating in free space. Based on the analytical solutions, explicit expressions governing the focusing distances of the Pearcey-Gaussian beams are found and verified by numerical simulations. For the linearly chirped Pearcey-Gaussian beam, it exhibits a uni-focusing behavior during propagation. Particularly, the focusing distance is independent on the linear chirp parameter and remains z_f = 2 unchanged. Of particular interest is that the quadratically chirped Pearcey-Gaussian beam focuses twice when the quadratic chirp parameter β < 0. The first and the second focusing distances are determined by z_f1 = 2/(1 - 4β) and z_f2 = -1/(2β), respectively. Furthermore, we numerically investigate the peak powers at the different focusing positions and find that as β increases, the peak powers at z_f1 and z_f2 linearly decrease. It is expected that the characteristics can be used for manipulating the focusing distances and the peak powers to generate an optical beam with high peak power by adjusting the chirp parameter β.

Experimental demonstration and investigation of vortex circular Pearcey beams in a dynamically shaped fashion

Optical vortex, typically characterized by a helical phase front, results in a possession of orbital angular momentum. In recent years, teleportation of the vortex mode using novel beams with peculiar features has gained great interest. Here, we experimentally demonstrate the propagation dynamics for a new class of the auto-focusing vortex circular Pearcey beam (VCPB), which is theoretically described by delivering the coaxial or off-axial spiral phases into the circular Pearcey beam (CPB), forming the crescent or bottle-like focal structure with self-rotation. Notably, such a hybrid beam with various types is experimentally obtained through a digital micromirror device (DMD) with the binary amplitude holography, and this DMD-based modulation scheme combined with controllable vortex modes enables dynamic switching among the VCPBs. We also measure the topological phase by interferometry and we explain the beam property on the basis of Poynting vector, showing a good agreement with the simulations. Further, the number, location and mode of embedded vortices could offer multiple dimensions of flexibility for target beam modulation, thus the experimentally controllable VCPBs will bring potential to high-speed optical communications and particle manipulations that require dynamic shaping.

Accelerating trajectory manipulation of symmetric Pearcey Gaussian beam in a uniformly moving parabolic potential

We derive analytical solutions that describe the one-dimensional displaced and chirped symmetric Pearcey Gaussian beam in a uniformly moving parabolic potential. The multiple effective manipulations of the beam, which are originated from the diverse configurations of the dynamic parabolic potential, are demonstrated. On the whole, the accelerating trajectory can transform into a linear superposition form of the oblique straight line and the simple harmonic motion. Meanwhile, we discuss the further modulation of the accelerating trajectory characteristics such as slope, amplitude and phase shift. Additionally, the extension into a two-dimensional scenario is also proposed. Our results theoretically improve the practical value of the Pearcey beam, and lead to potential applications in trajectory manipulation and particle manipulation.

Flexible autofocusing properties of ring Pearcey beams by means of a cross phase

In this Letter, we introduce a new class of angular dependent autofocusing ring Pearcey beams by imposing a cross-phase structure. Due to this structure, the beam exhibits a non-uniform abrupt autofocusing behavior. Unlike the properties of the ring Pearcey beam without a cross phase [Opt. Lett.43, 3626 (2018)OPLEDP0146-959210.1364/OL.43.003626], we can flexibly adjust the focal length of the beam and its focusing ability, as well as the direction of the ring Pearcey beams, with the help of only the cross-phase structure. Furthermore, the Poynting vectors are employed to demonstrate convincingly the beam-focusing mechanism. Such beams with these fascinating characteristics are anticipated to find potential applications in optical tweezing, three-dimensional printing, material processing, and so on.

Propagation of the first order annular Bessel Gaussian beams in a uniaxial crystal along the optical axis governed by the Pockels effect

We investigate the first order annular Bessel Gaussian beams propagating in a strontium barium niobate (SBN) crystal governed by the Pockels effect. The left-hand circularly polarized incident waves propagating along the optical axis in the crystal give rise to the right-hand circularly polarized vortex fields with a topological charge of 2. If an external dc field is applied along the optical axis of the SBN crystal, the anisotropy strength can be controlled rapidly, and the rotational invariance around the optical axis is still maintained. In this case, the normalized intensity in the focal region, the power exchange between left-hand and right-hand components, and the exchange between the spin and orbit contributions of the angular momentum flux can be manipulated. We also consider the case where the incident waves are linearly polarized along the x axis. The cylindrical symmetry of two Cartesian components is broken during propagation due to the anisotropy, and the intensity distribution as well as the polarization state of the beams can be regulated electrically.

Abruptly autofocusing chirped ring Pearcey Gaussian vortex beams with caustics state in the nonlinear medium

We simulate the propagation of the abruptly autofocusing chirped ring Pearcey Gaussian vortex (CRPGV) beams with caustics by modulating the phase of a circularly symmetric optical wavefront appropriately. The propagation characteristics of the CRPGV beams are explored in the Kerr medium. Different caustic surfaces of revolution which can be used as optical bottles are formed during the propagation. We also introduce the influence of the initial input power, the chirp factor and the stochastic type perturbations for the CRPGV beams during the propagation. Furthermore, the dynamics of the optical bottle and the breathers-like structures are explored in detail.

Propagation dynamics of Janus vortex waves

We study the propagation dynamics of Janus vortex wave under the action of a focusing lens based upon the formula of focused circular vortex Airy beams. Two dark foci would be generated under the action of a lens, and thus a perfect light hollow bottle could be formed. By controlling corresponding parameters, we could control the focal position and the relative intensity between the two focal intensities. The off-axis optical vortex (OV) would rotate rapidly in two focal regions, but keep still in the lens focus region. The angular displacement of OV in each focusing process is nearly π/2. (Note that the angular displacement for an off-axis OV in single focusing process of Gaussian beam is nearly π.) Two same OVs would repel to each other, but two opposite OVs would attract each other and annihilate at first focus plane in Janus vortex waves.

Effects of the modulated vortex and second-order chirp on the propagation dynamics of ring Pearcey Gaussian beams

The evolution of the chirped ring Pearcey Gaussian vortex (CRPGV) beams in free space is numerically investigated. The optical bottle beam and two-consecutive optical bottle beam can be directly generated from a ring Pearcey Gaussian beam with central vortices and the second-order chirp in free space. In particular, the focusing intensity will decrease when the vortices' locations are far away from the center of the beam or the topological charges are smaller. Our results show that the beam shapes, the normalized focusing intensity, and the focal length of the CRPGV beams can be controlled by choosing different beam parameters.

Abruptly autofocusing beams from phase perturbations having forced symmetry

A controllable manipulation of the energy distribution of caustic beams possessing rectangular symmetry is presented. The beams are designed from the spectral phase by adding a linear and/or quadratic perturbation having forced symmetry. This approach breaks the overall caustic structure into branches, allowing a fully controllable displacement of each branch. The caustic breaking leads to peculiar propagation configurations for rectangular beams. Among them, we highlight the abruptly autofocusing beam, which until now was exclusively associated to caustic beams with circular symmetry. Thereby, the abruptly autofocusing effect can be yielded for one-dimensional light sheets, contrary to what happens for circularly symmetric beams. The theoretical predictions are supported by experiments. Besides, the focus width of such rectangular beams can be reduced beyond the standard diffraction limit.