Optical Vortex Lattices Research Articles

Lattice generation utilizing fractional Talbot effect and high-order orbital angular momentum optical vortices

The concept of orbital angular momentum (OAM) has garnered significant attention from researchers since its discovery, with a steady uncovering of its properties over the past three decades. Initially overlooked, the role of OAM in the optical vortex lattice (OVL) has gained prominence due to recent scholarly efforts. This study delves into the modification of OAM by employing controlled topological charge to generate high-order OVL. Furthermore, it explores the Talbot effect within the context of multi-beam interference. The findings indicate that the interference of three beams of light results in the formation of both Kagome and Super-honeycomb lattices, whereas the interference of four beams leads to the emergence of the Lieb lattice. This research offers novel insights into light interference and light field regulation and its application.

Perfect Off-Axis Optical Vortex Lattice

Optical vortex lattices (OVLs) with diverse modes show potential for a wide range of applications, such as high-capacity optical communications, optical tweezers, and optical measurements. However, vortices in typical regulated OVLs often exhibit irregular shapes, such as being narrow and elongated. The resulting increase in asymmetry negatively impacts the efficiency of particle trapping. Additionally, the vortex radii expand with an increase in topological charge (TC), limiting the TC value of the vortices and hindering their ability to fully utilize orbital angular momentum (OAM). Herein, we propose an alternative approach to custom OVLs using off-axis techniques combined with amplitude modulation. Amplitude modulation enables the precise generation of an OVL with perfect vortex properties, known as a perfect off-axis OVL. Further, the number of vortices in the perfect off-axis OVL, the off-axis distances, and the TC can be freely modulated while maintaining a circular mode. This unique OVL will promote new applications, such as the complex manipulation of multi-particle systems and optical communication based on OAM.

Characterizing the propagation evolution of optical vortex lattices in astigmatic transformations of frequency-doubled laser modes.

We develop a wave representation to characterize the propagation evolution of vortex lattice beams, which are produced through a frequency-doubling process of various high-order laser modes, followed by mode conversion. Their phase fields and phase gradients are further analyzed to verify the topological charge for each isolated vortex, as well as the symmetry and net charges of the vortex lattices. In the experiment, we demonstrate the generation of frequency-doubled high-order modes by utilizing an off-center pumped solid-state laser combined with intracavity second-harmonic generation. Subsequently, we employ an astigmatic mode converter to transform the generated frequency-doubled laser modes, obtaining vortex arrays. The strong agreement between theoretical analysis and experimental data not only validates the derived formula but also confirms the creation and characteristics of the vortex lattice beams.

Generation of chiral optical vortex lattice for controlled aggregation of particles

The chiral light field has attracted great attention owing to its interaction with chiral matter. The generation of chiral light fields with rich structures has become crucial as it can expand application scenarios. Herein, we introduce a chiral optical vortex lattice. As a whole, the optical vortex lattice has a chiral intensity distribution, with each spiral arm having sub-vortices (chiral phase). By using an expansion factor to adjust the involute of a circular lattice, this helical optical vortex lattice can be continuously varied from a circular lattice. The chirality of intensity and phase can be controlled independently. Furthermore, the optical tweezers using the lattice demonstrate the capability of sub-vortices to manipulate particle movement, with the chiral intensity determining the trajectory of particle motion. As the lattice possesses both intensity and phase chirality, it may also find potential applications in tasks such as chiral structure microfabrication.

Switchable hybrid-order optical vortex lattice.

Optical vortex (OV) modulation is a powerful technique for enhancing the intrinsic degrees-of-freedom in structured light applications. Particularly, the lattices involving multiple OVs have garnered significant academic interest owing to their wide applicability in optical tweezers and condensed matter physics. However, all OVs in a lattice possess the same order, which cannot be modulated individually, limiting its versatile application. Herein, we propose, to our knowledge, a novel concept, called the hot-swap method, to design a switchable hybrid-order OV lattice, in which each OV is easily replaced by arbitrary orders. We experimentally generated the switchable hybrid-order OV lattice and studied its characteristics, including interferograms, retrieved phase, energy flow, and orbital angular momentum. Furthermore, the significant advantages of the switchable hybrid-order OV lattice are demonstrated through the independent manipulation of multiple yeast cells. This study provides a novel scheme for accurate control and modulation of OV lattices, which greatly facilitates the diverse applications of optical manipulation and particle trapping and control.

Generation of tunable vortex beams from a side-pumped Nd:YAG laser utilizing spot defect mirrors

High-order vortex lasers are important for high angular momentum quantum entanglement and high-resolution spatial detection. However, traditional spatial phase modulation for Gaussian beams have difficulties achieving high-order and continuously adjustable optical vortex output. In this study, a high-order vortex laser output of continuously adjustable topological charges between 1 and 9 was obtained by adjusting the cavity length in a side-pumped Nd:YAG oscillator with circular spot defects of different sizes etched on the surface of the cavity mirror. Its chirality was also controlled by slightly tilting the cavity mirror, and the mode changes under different cavity parameters and the factors limiting the output optical-vortex order in the side-pumping structure were analyzed. In addition, the generation of optical vortex lattice modes with multiple spatially separated OAMs was obtained based on the spot defect method by displacing the cavity mirror.

Tunable vortex beams generation in visible band via Pr3+:YLF laser with a spot defect

The generation of optical vortex beams with user-configurable topological charge and spatial profile is a topic of intense research due to the numerous potential applications for these types of laser beams. In this work, we demonstrate the direct generation of vortex laser beams with controllable topological charge and tunable spatial profile from a Pr3+:YLF laser cavity using a spot-defect technique. A theoretical model is established to examine the relationship between the topological charge of the generated vortex beam and how this relates to laser cavity parameters. Experimentally, the selective operation of first- and second-order vortex beams and tunable optical vortex lattices with one to four singularities at 607 nm can be achieved by adjusting the position of the defect spot. This work offers insight into methods for the generation of visible optical vortex beams with controllable topological charge and tunable singularities for a range of applications.

Generation and Talbot Effect of Optical Vortex Lattices with High Orbital Angular Momenta

AbstractOptical vortex lattices (OVLs) are gaining increased research attention owing to their unique features related to intensity and phase structure. Interference is a common method for generating an OVL. However, the topological charge (TC) of a single building block in an OVL is fixed and cannot be modulated, thereby limiting its applicability. This study entailed the use of phase multiplication to generate a high‐order OVL to facilitate the arbitrary modulation of its TC. The generated high‐order OVL exhibited the Talbot effect during transmission, and it transformed into a super‐honeycomb lattice at specific fractional Talbot lengths. In addition, an orbital angular momentum developed in the OVL; this has broad application prospects in optical micromanipulation. Further, a method for generating super‐honeycomb lattices is devised. The findings of this study enhances understanding of the Talbot effect and broaden the practical applicability of OVLs.

Generation of discrete higher-order optical vortex lattice at focus.

Higher-order vortices (HOVs) extend the dimensions of optical vortex regulation, which is of great significance in optical communication and optical tweezers. Herein, we demonstrate an alternative scheme to produce a HOV in the focus plane using multiple Laguerre-Gaussian (LG) beam interference, termed a discrete higher-order optical vortex lattice (DHOVL). The modulation depth of the DHOVL exceeds 2π. In this case, the topological charge (TC) of the DHOVL is determined by the difference of the phase period between the innermost and the outermost interference beams. Compared with a conventional HOV (CHOV), the vortex exists in a form of multiple unit singularities sharing a dark core. In addition, the average orbital angular momentum per photon of the DHOVL increases with increasing TC, surpassing that of the CHOV. This work provides a novel, to the best of our knowledge, scheme to produce a HOV, which will facilitate several advanced applications, including optical micromanipulation, optical sensing and imaging, and optical fabrication.

Generation of optical vortex lattices by in-line phase modulation with partially coherent light.

Of late, generation of different kinds of optical vortex lattices has been gaining much attention due to various applications. Several methods have been reported for the generation of optical vortex lattices using a coherent light source involving interferometric, diffractive, and pinhole phase plate methods. Owing to cost effectiveness and ease in optical implementation, these days use of incoherent or partially coherent light beams is becoming popular. In this study, we demonstrate generation of different kinds of optical vortex lattices through in-line modulation of phase distributions employing the phase concatenation approach and a light-emitting diode as a light source. It is a non-interferometric and flexible technique for the selection of the parameters that characterize the optical vortices and their arrays. The proposed method allows generation of an array of optical vortices of different topological charges with zero and non-zero radial indices having different symmetries.

Controllable customization of optical vortex lattices with coherent laser array

The customization of optical vortices with controllable structures is of fundamental importance for promoting various applications such as materials processing, optical communication, and optical tweezers. Here, a model of coherent beam combining (CBC) architecture was proposed to customize the exotic light beams array with controllable structures. The simulated results revealed that the optical vortex lattice (OVL) with multi-modes can be generated in the far field, and a proof-of-concept experiment was carried out for further verification. The experiment results were in a high degree of fidelity with the simulated results, indicating that the controllable structures could be generated efficiently by using the CBC architecture. The phenomenon of generated hollow beam having no orbital angular momentum (OAM) and the OVL copying can be observed. Furthermore, the phase detection experimental results verified the OAM states, the topological charge (TC) could be modulated from −2 to + 2. This work may present a new understanding of generating and manipulating the structured light fields.

Investigation on the Formation of Laser Transverse Pattern Possessing Optical Lattices

Optical lattices (OLs) with diverse transverse patterns and optical vortex lattices (OVLs) with special phase singularities have played important roles in the fields of atomic cooling, particle manipulation, quantum entanglement, and optical communication. As a matter of consensus until now, the OL patterns are generated by coherently superimposing multiple transverse modes with a fixed phase difference through the transverse mode locking (TML) effect. There are phase singularities in the dark area of this kind of OL pattern, so it is also called OVL pattern. However, in our research, it is found that some high-order complex symmetric OL patterns can hardly be analyzed by TML model. Instead, the analysis method of incoherent superposition of mode intensity could be applied. The OL pattern obtained by this method can be regarded as in non-TML state. Therefore, in this article, we mainly study the distinct characteristics and properties of OL patterns in TML and non-TML states. Through intensity comparison, interferometry, and beat frequency spectrum, we can effectively distinguish OL pattern in TML and non-TML states, which is of significance to explore the formation of laser transverse pattern possessing OL.

Averaged intensity and spectral shift of partially coherent chirped optical coherence vortex lattices in biological tissue turbulence

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Controllable Customization of Optical Vortex Lattices with Coherent Laser Array

Controllable Customization of Optical Vortex Lattices with Coherent Laser Array

Focal beam structuring by triple mixing of optical vortex lattices

On-demand generation and reshaping of arrays of focused laser beams is highly desired in many areas of science and technology. In this work, we present a versatile approach for laser beam structuring in the focal plane of a lens by triple mixing of square and/or hexagonal optical vortex lattices (OVLs). In the artificial far field the input Gaussian beam is reshaped into ordered arrays of bright beams with flat phase profiles. This is remarkable, since the bright focal peaks are surrounded by hundreds of OVs with their dark cores and two-dimensional phase dislocations. Numerical simulations and experimental evidences for this are shown, including a broad discussion of some of the possible scenarios for such mixing: triple mixing of square-shaped OVLs, triple mixing of hexagonal OVLs, as well as the two combined cases of mixing square-hexagonal-hexagonal and square-square-hexagonal OVLs. The particular ordering of the input phase distributions of the OV lattices on the used spatial light modulators is found to affect the orientation of the structures ruled by the hexagonal OVL. Reliable control parameters for the creation of the desired focal beam structures are the respective lattice node spacings. The presented approach is flexible, easily realizable by using a single spatial light modulator, and thus accessible in many laboratories.

Sculpturing spatiotemporal wavepackets with chirped pulses

Pulse shaping has become a powerful tool in generating complicated ultrafast optical waveforms to meet specific application needs. Traditionally, pulse shaping focuses on the temporal waveform synthesis. Recent interests in structuring light in the spatiotemporal domain rely on Fourier analysis. A space-to-time mapping technique allows us to directly imprint complex spatiotemporal modulation through taking advantage of the relationship between frequency and time of chirped pulses. The concept is experimentally verified through the generation of spatiotemporal optical vortex (STOV) and STOV lattice. The power of this method is further demonstrated by STOV polarity reversal, vortex collision, and vortex annihilation. Such a direct mapping technique opens tremendous potential opportunities for sculpturing complex spatiotemporal waveforms.

Generation of optical vortex lattices by a coherent beam combining system.

Owing to the unique features in intensity and phase structures, optical vortex lattices (OVLs) have attracted intensive attention and promoted various applications. However, the power scaling of OVLs always presents a critical challenge. Here we take advantage of the brightness enhancement of coherent beam combining (CBC) technology and propose an architecture for creating OVLs based on the CBC system. In the experiment, by utilizing the stochastic parallel gradient descent algorithm, the dynamic phase noises were compensated. The desired piston phase shifting of each element for tailoring the structured wavefront was implemented by the liquid crystal. When the system in a closed loop, hexagonal close-packed OVL consists of spatially distributed orbital angular momentum, beams can be generated in the far-field. This work is an important step toward future implementation of high-power structured light beams.

Optical Vortices: 3D Optical Vortex Lattices (Ann. Phys. 7/2021)

In article number 2100114, Denis Ikonnikov and co-workers report the results of Fresnel diffraction of light beams with a topological charge on a 2D regular amplitude transparency mask. The cover illustrates the complex optical field behind the grating, representing all 3D lattice of optical vortices, which is formed owing to the Talbot effect. These results are confirmed by the experimental reconstruction of all 3D optical vortex lattices. It is shown that the optical vortices are created and annihilated during light propagation behind the mask with the preservation of the total topological charge. The 3D optical vortex lattices are considered to be promising for transport and manipulation of multiple micro-objects.

Optical vortex lattice mode generation from a diode-pumped Pr3+:LiYF4 laser

We report on the direct generation of optical vortex lattice (OVL) modes from a diode-pumped Pr3+:LiYF4 (Pr:YLF) laser achieved by employing off-axis (transverse) and defocused (longitudinal) pumping geometries in the laser medium. OVL modes with more than 40 phase singularities are generated. The experimentally observed OVL modes are well supported by a theoretical analysis based on the superposition of Hermite-Gaussian modes. We also discuss the intracavity frequency doubling of the OVL modes. The proposed OVL mode laser system can be applied to fundamental optical science and advanced material engineering.

Optical vortex lattice: an exploitation of orbital angular momentum

Abstract Generally, an optical vortex lattice (OVL) is generated via the superposition of two specific vortex beams. Thus far, OVL has been successfully employed to trap atoms via the dark cores. The topological charge (TC) on each optical vortex (OV) in the lattice is only ±1. Consequently, the orbital angular momentum (OAM) on the lattice is ignored. To expand the potential applications, it is necessary to rediscover and exploit OAM. Here we propose a novel high-order OVL (HO-OVL) that combines the phase multiplication and the arbitrary mode-controllable techniques. TC on each OV in the lattice is up to 51, which generates sufficient OAM to manipulate microparticles. Thereafter, the entire lattice can be modulated to desirable arbitrary modes. Finally, yeast cells are trapped and rotated by the proposed HO-OVL. To the best of our knowledge, this is the first realization of the complex motion of microparticles via OVL. Thus, this work successfully exploits OAM on OVL, thereby revealing potential applications in particle manipulation and optical tweezers.