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

Comparison of focusing property and radiation force between autofocusing Bessel beams and focused Gaussian beams

As abruptly autofocusing beams, autofocusing Bessel beams (ABBs) have been proven to be a class solution for the Helmholtz equation [Opt. Express31, 33228 (2023)10.1364/OE.500383]. In this paper, we use the Fresnel number as the basic parameter and accurately compare the focusing property and radiation force of ABBs versus focused Gaussian beams (FGBs) under the same Fresnel number. Unlike FGBs, ABBs can achieve autofocusing without the need for an initial focusing phase. Our analysis of the beam width defined by power in the bucket, revealed that FGBs exhibit uniform focusing along the straight line, whereas ABBs demonstrate accelerated focusing along the elliptic curve. At the same Fresnel number, FGBs exhibit a higher peak intensity in the focal plane, yet ABBs excel in gradient force on particles. In comparison to FGBs, ABBs exhibit smaller potential well widths, allowing for stable and precise trapping of high refractive index particles at the focal point. While FGBs are considered suitable for laser processing and ablation due to their high peak power density, ABBs possess significant advantages in optical manipulation due to their great gradient force. Furthermore, we conduct a comparative analysis between ABBs and circular Airy beams (CABs). The peak intensity and gradient force exhibited by CABs are slightly lesser than those of ABBs. CABs are appropriate for multi-point trapping along the axis, whereas ABBs are more suited for precise single-point trapping.

Generation of ultra-intense vortex laser from a binary phase square spiral zone plate

With the development of ultra-intense laser technology, the manipulation of relativistic laser pulses has become progressively challenging due to the limitations of damage thresholds for traditional optical devices. In recent years, the generation and manipulation of ultra-intense vortex laser pulses by plasma has attracted a great deal of attention. Here, we propose a new scheme to produce a relativistic vortex laser. This is achieved by using a relativistic Gaussian drive laser to irradiate a plasma binary phase square spiral zone plate (BPSSZP). Based on three-dimensional particle-in-cell (3D-PIC) simulations, we find that the drive laser has a phase difference of π after passing through the BPSSZP, ultimately generating the vortex laser with unique square symmetry. Quantitatively, by employing a drive laser pulse with intensity of 1.3 × 1018~W/cm2, a vortex laser with intensity up to 1.8 × 1019~W/cm2, and energy conversion efficiency of 18.61% can be obtained. The vortex lasers generated using the BPSSZP follow the modulo-4 transmutation rule when varying the topological charge of BPSSZP. Furthermore, the plasma-based BPSSZP has exhibited robustness and the ability to withstand multiple ultra-intense laser pulses. As the vortex laser generated via the BPSSZP has high intensity and large energy conversion efficiency, our scheme may hold potential applications in the community of laser-plasma, such as particles acceleration, intense high-order vortex harmonic generation, and vortex X/γ-ray sources.

Particle manipulation with twisted circle Pearcey vortex beams

In this Letter, we present an approach for particle manipulation utilizing twisted circle Pearcey vortex beams. These beams are modulated by a noncanonical spiral phase, which allows for flexible adjustment of rotation characteristics and spiral patterns. Consequently, particles can be rotated around the beam's axis and trapped with a protective barrier to avoid perturbation. Our proposed system can quickly de-gather and re-gather multiple particles, enabling a swift and thorough cleaning of small areas. This innovation opens up new possibilities in particle cleaning and creates a new platform for further study.

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.

Multiple-dimensional multiplexed holography based on modulated chiro-optical fields

Orbital angular momentum (OAM) multiplexing technology has been developed in the optical information encryption fields. Here, the modulated chiro-optical OAM (MC-OAM) holography is proposed to further improve information security capacity, which integrates the OAM multiplexing technology with the chiro phase modulation. The orthogonality of the axicon parameter, chiro coefficient and rotation angle modulating the chiro phase distributions are analyzed, respectively, which demonstrate their potential usages as extra degrees of freedom besides the topological charge (TC). Those three parameters combining TC serve as four optical keys, which provides a four-dimensional spatial multiplexing method for information security. Furthermore, we have demonstrated that TC minimum interval of the fractional MC-OAM reaches 0.01. The experimental and simulation results exhibit the essential properties in selectivity and multiplexing of MC-OAM holography. This method can significantly increase the holographic information capacity and safety and inspire widespread applications, such as display, information security and communication.

Generation and control of tornado waves by means of ring swallowtail vortex beams

Tornado waves (ToWs), which refer to a light that accelerates and twists over both the radial and the angular directions, have gained a great deal of interest since the concept was introduced by Brimis et al [Opt. Lett.45, 280 (2020)10.1364/OL.45.000280]. In this paper, we superimpose two pairs of ring swallowtail vortex beams (RSVBs) to generate ToWs and we call them tornado swallowtail waves (ToSWs). Each pair consists of RSVBs while carrying orbital angular momentum of opposite helicity and slightly different with the radius of the main ring of RSVBs. The waves spiral forward and reveal intensity maxima, exhibiting a tornado-like intensity profile during propagation. Meanwhile, the angular acceleration of the ToSWs is illustrated via tracing the angular position of the high-intensity main lobes. It is found that ToSWs present very high values of angular acceleration. Compared with typical tornado waves, ToSWs are more diverse and tunable, giving a new degree of freedom to tailor the propagation dynamics due to the flexibility of the swallowtail diffraction catastrophe. In addition, we confirm such waves experimentally and the results match well with the numerical ones. Also, we demonstrate the ability of optical manipulation of ToSWs for the first time in that they allow for particles not only to be trapped but also to be rotated. Finally, we analyze the poynting vectors and power exchange of ToSWs to demonstrate convincingly the physical mechanism.

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.