Optical Vortex Array Research Articles

Production of high-purity non-diffracting optical vortex arrays with high topological charge

In this paper, we have realized the high purity non-diffracting optical vortex arrays with a high topological charge using quasi-symmetrical plane waves for the first time. The triangular vortex arrays with l = ±2 can be generated by six quasi-symmetrical plane waves, and the square vortex arrays with l = ±3 can be generated by eight quasi-symmetrical plane waves. The adjacent vortex units have opposite topological charges. We have also obtained the relations between the periods of the field formed by the six/eight quasi-symmetrical plane waves and the periods of the field formed by the three/four symmetrical plane waves. The simulation and experimental results demonstrate the feasibility of this method.

Image authentication with exclusive-OR operated optical vortices

Optical vortices carrying orbital angular momentum have drawn much attention because they provide high-dimensional encoding. Employing an array of optical vortices, we demonstrate an authentication verification system. For security authentication, an exclusive-OR logic operation has been implemented employing a light beam consisting of an array of vortices. A liquid crystal spatial light modulator has been used to generate orthogonal states of optical vortices. The proposed technique can provide a secure method of authentication with straightforward implementation. We have presented simulation and experimental results to verify the proposed scheme.

Generating Optical Vortex Array Laser Beams of Superimposing Hermite–Gaussian Beams with a Dual–Phase Modulation Digital Laser System

This study presents an efficient and practical intra-cavity approach for selectively generating vortex array laser beams employing a dual-phase modulation digital laser system, which has not yet been completed in single-phase modulation digital laser. The stable optical vortex array laser beams were formed by superimposing cavity Hermite–Gaussian (HG) eigenmodes. In particular, when the selected cavity HG modes shared the same Gouy phase, the resulting optical vortex beam could preserve its light field pattern, thereby maintaining the optical vortex properties in the near and far fields. Numerical results demonstrated that employing dual-phase modulation could establish optimal boundary conditions for the selection of HG modes within the cavity, successfully generating various vortex array laser beams. The experimental validation of the proposed method confirmed the ability to select optical vortex array lasers solely by controlling the loaded phase of the dual-phase modulation digital laser. These results demonstrate the ability of digital lasers to generate and dynamically control optical vortex array lasers.

Archimedes spiral optical vortex array emitter.

Optical vortex arrays (OVAs) are important for large-capacity optical communications, optical tweezers, and optical imaging. However, there is an urgent need to generate an optical vortex emitter to construct a specific OVA with a functional structure for the accurate transport of particles. To address this issue, we propose an Archimedes spiral OVA emitter that uses an Archimedes spiral parametric equation and coordinate localization techniques to dynamically regulate the position of each optical vortex. We discuss the phenomena of the location coordinates and Archimedes spiral from unclosed to closed on the OVA emitter. Furthermore, the propose of multiple OVA emitters demonstrates a chiral structure that has the potential for optical material processing. This study lays the foundation for generating OVAs with functional structures, which will facilitate advanced applications in the complex manipulation, separation, and transport of multiple particles.

Robust high-order petal-mode laser with tunable topological charge pumped by an axicon-based annular beam

In this work, we demonstrate a watt-level laser producing high-order, petal-shaped output modes with tunable topological charge, by using an axicon-based divergent annular pump beam. The topological charge of the output beam could be varied in the range of 34–72 by adjusting the position of the Nd:YVO4 crystal relative to the focal plane of the pump beam. The highest order petal-mode beam generated from the system had a topological charge of 72 and a power of 1.3 W. The highest output power up to 2.1 W with a topological charge of 34 was achieved at an absorbed pump power of 5.8 W. The generated output modes were observed to be robust under power scaling and on propagation, with the same spatial profiles being maintained in the near- and far-fields. We anticipate that this system design may find use as a laser source in applications such as 3D optical trapping, fabrication of optical vortex arrays, optical communications, and high-sensitivity spatial measurement.

Generation of arbitrarily structured optical vortex arrays based on the epicycle model.

Optical vortex arrays (OVAs) are complex light fields with versatile structures that have been widely studied in large-capacity optical communications, optical tweezers, and optical measurements. However, generating OVAs with arbitrary structures without explicit analytical expressions remains a challenge. To address this issue, we propose an alternative scheme for customizing OVAs with arbitrary structures using an epicycle model and vortex localization techniques. This method can accurately generate an OVA with an arbitrary structure by pre-designing the positions of each vortex. The influence of the number and coordinates of the locating points on customized OVAs is discussed. Finally, the structures of the OVA and each vortex are individually shaped into specifically formed fractal shapes by combining cross-phase techniques. This unique OVA will open up novel potential applications, such as the complex manipulation of multiparticle systems and optical communication based on optical angular momentum.

Pulsed Optical Vortex Array Generation in a Self-Q-Switched Tm:YALO3 Laser.

Optical vortex arrays are characterized by specific orbital angular momentums, and they have important applications in optical trapping and manipulation, optical communications, secure communications, and high-security information processing. Despite widespread research on optical vortex arrays, the 2 μm wavelength range remains underexplored. Pulsed lasers at 2 μm are vital in laser medicine, sensing, communications, and nonlinear optic applications. The need for 2 μm-pulsed structured optical vortices, combining the advantages of this wavelength range and optical vortex arrays, is evident. Therefore, using just three elements in the cavity, we demonstrate a compact self-Q-switched Tm:YALO3 vortex laser by utilizing the self-modulation effect of a laser crystal and a defect spot mirror. By tuning the position of the defect spot and the output coupler, the resonator delivers optical vortex arrays with phase singularities ranging from 1 to 4. The narrowest pulse widths of the TEM00 LG0,-1, two-, three-, and four-vortex arrays are 543, 1266, 1281, 2379, and 1615 ns, respectively. All the vortex arrays in our study have relatively high-power outputs, slope efficiencies, and single-pulse energies. This work paves the way for a 2 μm-pulsed structured light source that has potential applications in optical trapping and manipulation, free-space optical communications, and laser medicine.

Optical vortex array: generation and applications [Invited

Optical vortex array: generation and applications [Invited

Broadband multifunctional metasurfaces enabling polarization multiplexed focused vortex array generation

Metasurfaces are ultrathin artificially engineered structures exquisitely designed to tailor the wavefront, polarization, and amplitude of incident light, offering a versatile platform for implementing compact and integrated photonics devices. Metasurface-based structured light generation has gained considerable attention in the scientific community for its various exotic applications, including optical communication, particle manipulation, and high-resolution lithography. State-of-the-art design techniques include polarization multiplexing, multiple vortices beam generation, and vortex arrays. However, there needs to be more techniques for generating polarization switchable vortex arrays, despite the apparent advantages in significant application fields, necessitating a simple design technique. Here, we present a straightforward design technique utilizing computer-generated holography (CGH) and photonic spin Hall effect (PHSE) to realize a metadevice platform capable of generating broadband multiple optical vortex arrays with switchable polarization output. Our approach involves designing phase masks for the vortex arrays using CGH, which are then encoded onto the metasurface. By leveraging PSHE, the designed metasurfaces produce the desired optical response depending on the input polarization state. Using the proposed design technique as proof of concept, different all-dielectric metasurfaces capable of generating optical vortex arrays of different dimensions are demonstrated. The results verify the effectiveness of the proposed methodology. The design has potential applications in data communications, storage, quantum computation, nanoscale physical manipulation, and microscopy.

Three-dimensional implementation of multi-mode fractional-order elliptical perfect optical vortex arrays

Fractional-order vortex beams possess unique spin and orbital angular momentum structure, and have significant applications in various fields. Nevertheless, the construction and tuning of these beams require high-precision optical devices and systems that are challenging to implement. Here, we propose a simple and effective method for realizing multi-mode independent modulation of fractional-order vector elliptical perfect optical vortices. The linear modulation of the EPOV ring is demonstrated. By combining the mode extraction with optical pen, multi-mode independent modulation of fractional-order elliptical perfect optical vortex arrays are successfully constructed, including position, quantity, ellipticity, topological charge, and polarization order. The experimental results are highly consistent with the numerical simulation results. We also demonstrate the implementation process of constructing multiple fractional-order EPOV arrays in three-dimensional space. This work provides a simple and feasible solution for the control of complex structured light fields and is expected to play an important role in optical trapping, optical communication, optical imaging, and quantum optics.

Ultrafast vortex arrays generated from a mode-locked oscillator with dispersion management.

Herein, we demonstrate the generation of optical vortex arrays pulses using a Sagnac common-path interferometric vortex generator. Hermite-Gaussian (HG) modes with different orders are initially obtained from a SESAM mode-locked laser in the positive dispersion regime. Then, in the interferometric vortex generator, by controlling the phase difference and sheering displacement between two HG modes, optical vortex pulses with different numbers of phase singularities are generated through superposition. The generated HG10 mode has a pulse width of 2 ps and maximum energy of 0.75 nJ. One-dimensional vortex arrays and triangular vortex arrays are also generated, which are formed by HGm0 and HG0n modes, respectively. This work has potential applications in the massive manipulation of microparticles, optical communication, and so on.

High-quality tunable optical vortex arrays with multiple states of orbital angular momentum

We demonstrate the generation of high-quality optical vortex arrays (OVAs) with multiple states of orbital angular momentum (OAM) by uploading computer-generated holograms that are specially designed onto a liquid crystal spatial light modulator. The method of encoding both the amplitude and phase of an optical field into a phase-only holograms enables precise control of spatial transverse vortex modes. By combining the spiral, checkerboard and blazed-grating phase, the zero-order diffracted light can be efficiently suppressed while energy is redistributed onto higher orders to improve the quality of vortex array. Furthermore, the intensity distribution and spatial position can be flexibly modulated as well as OAM state of each vortex laser beam. It significantly increases the versatility of OAM, broadening its application in high-capacity optical communication and manipulation of multiple particles.

Modulating and identifying an arbitrary curvilinear phased optical vortex array of high-order orbital angular momentum

Vortex beams can be used in optical communication, imaging, and processing applications. In this study, we generate a phased optical vortex array with high-order orbital angular momentum (OAM) based on a phased Gaussian optical array and high-order phase multiplication. We then analyze the OAM mode distribution using the OAM spectrum expansion, and the number of high-order phase singularities in the array verified in interference experiments. Our results substantiate the feasibility of generating a high-order optical vortex array using this method. At the same time, because the phase Gaussian optics array that forms the phased optical vortex array is discrete and separable, we can use the phase Gaussian optics array with different phase differences to generate the phased optical vortex array with different phase gradients. The shape of the generated optical vortex array can be arranged along any curve. The phase singularity and OAM distributions at high orders are also detailedly analyzed. The ability to control the high-order OAM and phase structure has possible applications in particle manipulation and free-space optical communication.

Color image information transmission based on elliptic optical vortex array encoding/decoding.

A multichannel high-dimensional data encoding/decoding scheme based on composite elliptic optical vortex (EOV) arrays is proposed. By exploiting the rotation angle of the EOV, a 4 × 4 composite EOV array is used for high-dimensional data encoding. The conjugate symmetric extension Fourier computer-generated holography algorithm with controllable reconstruction focus is used to assign different reconstruction focus to the data of the three channels (R, G, and B) of the color image. Then, the data of the three channels is transmitted simultaneously by a single hologram to further improve the transmission efficiency. At the receiver, the initial information sequence is decoded by directly identifying the captured intensity patterns with a deep learning-based convolutional neural network. In the experiment, a 128 × 128-pixel color image is successfully transmitted, which confirms the feasibility of our proposed encoding/decoding scheme. This method has great potential for future high-capacity optical communications.

Inner-cavity generation of mid-infrared optical vortex arrays from an Er:CaF2 laser

We demonstrate the inner-cavity generation of mid-infrared optical vortex arrays from an Er:CaF2 laser. By shifting the position of the defect point on the input mirror, multiple transverse modes simultaneously oscillated in the cavity and constituted vortex arrays by transverse mode locking. The maximum output power of TEM00 mode could reach 440 mW with a low threshold of 463 mW. The maximum output powers of LG0,1, the 1 × 2 and the 2 × 2 vortex arrays were 254 mW, 131 mW, and 117 mW, respectively. The chirality of the vortex arrays could be reversed by slightly adjusting the geometric loss of the cavity. The light intensity distribution, interference, and phase distribution were simulated and they were in good accordance with the experimental results. This method provides deep insight into inner-cavity generation of vortex arrays in mid-infrared regime.

Multi-dimensionally modulated optical vortex array

We report on a multi-dimensionally modulated optical vortex array (MMOVA). First, we propose a modified transform technique of the lattice coordinates, which possesses more modulated parameters. Then, the MMOVA is experimentally generated and the optical vortex (OV) is verified and determined by the interference method. Besides the whole structural transformation of MMOVA, the modulation of local part and even the individual OV are executed, which demonstrate the distinct capacity of MMOVA over that of the existing optical vortex array (OVA). The proposed MMOVA provides a novel scheme to generate OVAs with higher modulated dimensions, which will open up potential applications for multiple micro-particles manipulation.

Vortex array generation based on quasi-Talbot effects.

A lens-less method for generating vortex arrays with tunable parameters is proposed based on quasi-Talbot effects. By illuminating a two-dimensional periodic sinusoidal grating with a vortex beam carrying a fourth-order cross-phase, the continuous vortex array structure can be generated in the Fresnel diffraction region. Due to the shaping effect of the fourth-order cross-phase on the vortex beam, by changing the constant parameter of the fourth-order cross-phase, it is possible to shape the generation of optical vortex arrays at different positions. This will somewhat broaden the flexibility of the lens-free optical vortex array in terms of generation position. In addition, the generation of polygonal optical vortex arrays is achieved by higher-order cross-phases of different orders. This technique has potential applications in various fields such as optical tweezers, multi-particle screening, microscopic manipulation, etc.

Detection of a spinning object using a superimposed optical vortex array.

The optical vortex (OV) carries unique orbital angular momentum (OAM) and experiences a Doppler frequency shift when backscattered from a spinning object. This rotational Doppler effect (RDE) has provided a solution for the non-contact detection of rotating motion. The reported RDE researches mainly use a single OV that generates frequency shifts proportional to its topological charge and has low robustness to light incidence. Here, we show the distinctive RDE of superimposed optical vortex array (SOVA). We analyze the holistic OAM of SOVA which is represented in terms of a superposition of azimuthal harmonics and displays a unique modal gathering effect. In the experiment of RDE, the frequency shift signals of SOVA show a precise mapping to the OAM modes and the modal gathering effect contributes to enhance the amplitude of signals, which has the potential to enhance robustness against non-coaxial incidence. This finding provides a new aspect of RDE and a pioneered example for introducing various SOVAs into rotation detection.

Mid-infrared vortex array generation with a tunable singularity in an Er:YAP laser

Optical vortex arrays are structured light fields with multiple phase singularities that have attracted considerable attention in recent years. Here, we demonstrate the direct generation of an optical vortex array with tunable singularity from a mid-infrared Er: yttrium aluminum perovskite laser under the annular-pumping regime. An axicon combined with a plano–convex lens is used to reshape the pumping beam into an annular one to match the different orders of the Laguerre–Gaussian mode. By adjusting the pump power and the lateral displacement of the gain medium, a tunable vortex array with one to four singularities is obtained in the ∼3-μm mid-infrared wavelength region. The lasing characteristics of the mid-infrared vortex arrays are evaluated and discussed. The experimental results can shed some light on the generation of mid-infrared optical vortex laser arrays and their applications.

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.