Bessel Gaussian Research Articles

Free-space propagation of double-ring perfect optical vortex beams

Abstract Single-ring perfect optical vortex (SR-POV) beams have received significant attention from the singular optics community due to their topological charge (TC)-independent ring radius, which offers certain advantages over conventional vortex beams such as Laguerre-Gaussian (LG) and Bessel-Gaussian (BG) beams in applications like particle trapping, optical communication, and imaging. However, the generation of double-ring perfect optical vortices (DR-POVs), embedded with two TCs, offers greater advantages over SR-POVs in terms of robustness during propagation and enhanced channel capacity in communication networks. In our theoretical analysis, we first highlight the differences between true and approximated representations of DR-POV beams. We then investigate the propagation of DR-POV beams in free-space, demonstrating how their evolution is influenced by factors such as the TCs of the inner and outer rings, the ratio of the beam radius to beam width at the waist plane. Similar to SR-POV beams, DR-POV beams exhibit non-diffracting behavior over short propagation distances, with little to no impact on the beam’s propagation when the TCs of the inner and outer rings are altered. However, phase wandering characteristics are observed, even over short propagation distances. Our research could find potential applications in the field of free-space optical communication.

Spatial filtering and optimal generation of high-flux soft x-ray high harmonics using a Bessel–Gauss beam

In recent years, significant advancements in high-repetition-rate, high-average-power mid-infrared laser pulses have enabled the generation of tabletop high-flux coherent soft x-ray harmonics for photon-hungry experiments. However, for practical applications, it is crucial to effectively filter out the driving beam from the high harmonics. In this study, we leverage the distinctive properties of a Bessel–Gauss (BG) beam to introduce a novel approach for spatial filtering, specifically targeting soft x-ray harmonics, releasing with a high-photon flux simultaneously. Our simulations reveal that by finely adjusting the focus geometry and gas pressure, the BG beam naturally adopts an annular shape, emitting high harmonics with minimal divergence in the far field. To achieve complete spatial separation of the driving beam and harmonic emissions, we pinpoint the optimal gas pressure and focusing geometry, particularly under overdriven laser intensities, for achieving good phase matching of harmonic emissions from short-trajectory electrons within the gas medium when the exact ionization level is higher than the “critical” value. Additionally, we establish scaling relations for sustaining optimal phase-matching conditions crucial for spatially separating the driving laser and the high-harmonic field, especially as the wavelength of the driving laser increases. Furthermore, our analysis demonstrates a substantial enhancement of harmonic yields by at least one order of magnitude compared to a truncated Gaussian annular beam. We also show that under accessible experimental conditions, soft x-ray photon flux up to 1010 photons/s at 250 eV can be achieved. The utilization of the BG beam opens up a promising pathway for the development of high-flux attosecond soft x-ray light sources, poised to serve a wide range of applications.

Guiding properties of Bessel–Gaussian and super-Gaussian pulses in inhomogeneous parabolic plasma channels

The guidance and stable propagation of laser pulses over many Rayleigh lengths are crucial for the plasma electron acceleration in the laser wakefield accelerators. Using plasma channels with specific characteristics can lead to the proper guidance of the laser pulse. Here, quasi-three-dimensional particle-in-cell (PIC) simulations are performed to investigate the guidance of Bessel–Gaussian pulse (BGP) of zeroth order and super-Gaussian pulse (SGP) of 3rd and 4th orders in an axially and radially inhomogeneous plasma channel. The effects of the channel radius and depth, the laser wavelength and initial spot size, and the plasma channel inhomogeneity on the guidance of the laser pulse are also examined. The results indicate that the guidance of a laser pulse in the plasma channel depends on the pulse profile, and under certain conditions, the pulses can be guided with the least variation of spot size in the inhomogeneous plasma channel. It is shown that the channel depth and the initial laser spot size are very effective in pulse guiding, as the values of these parameters increase, the pulse guidance is done better. In addition, the results show that the guidance of laser pulse is dependent on the type of plasma inhomogeneity represented by three different kinds of initial conditions, as considering the nonlinear-axial inhomogeneity in the parabolic plasma channel can lead to more convergence than the axially homogeneous and linear-axially plasma density profiles.

Investigation on the transmission attenuation of Bessel-Gaussian beams in a dusty environment

This paper delves into the transmission dynamics of Bessel-Gaussian (BG) beams in three distinct dusty environments, leveraging the Generalized Lorenz-Mie Theory (GLMT) alongside a single scattering model for a comprehensive analysis. Through numerical simulations, the study explores the interaction between dust particle scattering and the attenuation and transmittance behaviors of BG beams, elucidating the influences of varying particle concentrations and visibility conditions typical of floating dust, blowing sand, and sandstorms. The findings reveal numerous determinants, including particle number concentration, optical visibility, wavelength, orbital angular momentum (OAM) modes, waist radius, cone angle, and polarization states, which significantly affect the transmission performance of BG beams in dusty conditions. Notably, the attenuation rate decreases with increasing wavelengths and higher OAM modes, thereby extending effective transmission distances. Furthermore, the strategic use of linear polarization emerges as an optimal approach for enhancing BG beam transmission efficiency in dust-rich environments. These insights are crucial for optimizing BG beam transmission in real-world applications, marking a significant advancement in the field.

Focus shaping of circularly polarized Bessel–Gaussian vortex beam with binary axicon for nanoparticles trapping

Focus shaping of circularly polarized Bessel–Gaussian vortex beam with binary axicon for nanoparticles trapping

Perfect vortex beams generation based on reflective geometric phase metasurfaces

Perfect vortex beam (PVB) is a propagating light field with radial intensity distribution independent of topological charge and carrying orbital angular momentum (OAM). PVBs can be generated through the Fourier transformation of a Bessel-Gaussian (BG) beam, which traditionally requires a precisely aligned optical setup consisting of a spiral phase plate, a conical lens, and a Fourier lens. However, such traditional schemes are usually bulky and unstable. Here, we have utilized a method that differs from conventional approaches, employing metasurfaces designed as planar Pancharatnam-Berry (PB) phase elements to substitute for all the required components. Unlike traditional methods based on reflective or refractive elements, metasurface elements can significantly reduce the system's footprint. Because the use of metallic metasurfaces allows for a more flattened design plane, in this paper, we have demonstrated the generation of PVB within the 8 GHz microwave frequency band based on a single-layer metallic metasurface. The metasurface is composed of a square ring metal structure, which can serve as a half wave plate to provide the required geometric phase distribution for incident circularly polarized light to generate PVB. By rigorously optimizing the parameters of the square-ring structures, we have generated vortex beams carrying OAM with different topological charges. These vortex beams exhibit a constant radial intensity distribution, which validates their "perfect" characteristics. In addition, we also extracted the mode purity of different vortex beams, so that the mode states of different vortex beams can be distinguished. These results provide broader value for the application of perfect vortex beams in communication.

Bessel–Bessel–Gaussian vortex laser beams

Abstract We obtain and investigate Bessel–Bessel–Gaussian vortex beams (BBG beams) with the complex amplitude being equal to a product of the Gaussian function with two Bessel functions, whose arguments are expressed as complicated radicals including the cylindrical coordinates and a free parameter that defines the shape of the intensity distribution. If this parameter is small, the intensity has the shape of an inhomogeneous ring. For larger values of this parameter, the intensity has the shape of two arcs or ‘crescents’, oriented by their concave sides to each other. The complex amplitude of such beams is derived in explicit form for an arbitrary distance from the waist. We demonstrate that the BBG beams rotate upon propagation anomalously fast: at a distance much shorter than the Rayleigh length, the intensity distribution is already rotated by almost 45°, whereas typically, the rotation angle of vortex Gaussian beams is equal to the Gouy phase. It is also shown that the parameter of the BBG beam allows controlling its topological charge (TC): when the parameter value is positive and increases, the beam TC also increases stepwise by an even number. Besides, we study two other similar vortex BBG beams: either with four local intensity maxima, lying on the Cartesian coordinates axes, or with one intensity maximum with a crescent shape, whose center is on the horizontal axis. The derived three new families of asymmetric vortex laser beams, whose complex amplitude is described by explicit analytical expressions at an arbitrary distance from the waist, extend the variety of laser beams that can be used for manipulating and rotating microparticles, free space data transmission, and in quantum informatics.

Propagation dynamics and radiation forces of circular Bessel Gaussian beams carrying power-cotangent-phase vortices.

In this paper, the circular Bessel Gaussian beams (CBGBs) carrying power-cotangent-phase vortices are firstly introduced, whose propagation dynamics are explored theoretically and experimentally. The number of spiral lobes, rotation direction, rotation angle, and shape of the new type of beam can be flexibly modulated by controlling multiple parameters of power-cotangent-phase vortices. Accordingly, the effect of multiple beam parameters on abruptly autofocusing ability is quantified and compared by using the K-value curve that is described by ratio Im/I0, where Im and I0 correspond to the maximum intensities at different propagation distance and the initial plane, respectively. The physical mechanism of intensity distribution variation depended on the propagation distance and power-cotangent-phase parameters are also demonstrated convincingly by employing the Poynting vector. In addition, the advantages and applications of the proposed beam as a tool for the Rayleigh particle manipulation are analyzed theoretically. It is expected that the introduced beam can be useful for extending applications of optical vortices, particularly for multiple particle manipulation.

Field-resolved space–time characterization of few-cycle structured light pulses

Accompanied by the rapid development of ultrafast laser platforms in recent decades, the spatiotemporal manipulation of ultrashort laser pulses has attracted much attention due to the potential for cutting-edge applications of structured light, including optical tweezers, optical communications, super-resolution imaging, time-resolved spectroscopy in molecules and quantum materials, and strong-field physics. Today, techniques capable of characterizing the full spatial, temporal, and polarization state properties of structured light are strongly desired. Here, we demonstrate a technique, termed 3D TIPTOE, for characterizing structured mid-infrared waveforms, which uses only a two-dimensional silicon-based image sensor as both the detector and the nonlinear medium. By combining the advantages of the sub-cycle time resolution afforded by nonlinear excitation and the spatial resolution inherent to the two-dimensional sensor, the 3D TIPTOE technique allows full characterization of structured electric fields, significantly reducing the complexity of detection compared to other techniques. The validity of the technique is established by measuring both few-cycle Bessel–Gaussian pulses and radially polarized femtosecond vector beams.

Information propagation of focus wave mode localized waves in anisotropic turbulent seawater

The evolution of the information transfer capability of an optical system for underwater focused wave mode localized wave (FWMLW) in anisotropic weakly turbulent absorbing seawater is studied. By developing the probability distribution function as well as the detection probability of the vortex modes carried by the FWMLW and the average bit error rate of the FWMLW underwater system, the information capacity of the FWMLW system with a pointing error is modeled. Through a numerical analysis of the effects of turbulent seawater and optical system parameters on the built light intensity, the detection probability, and the information capacity models, we find that the FWMLW system has an optimal delay time determined by the spectrum bandwidth when the spectrum bandwidth is greater than 1. The information capacity of the FWMLW system is higher than that of the X localized wave system under the same turbulent seawater channel condition, and FWMLW is a better optical signal source for vortex mode division multiplexing underwater systems than a Bessel–Gaussian beam.

Performance evaluation and comparative research of underwater wireless optical communication system by using different structured beams

Structured beams have attracted increasing interest in free-space and fiber-based optical communications. Underwater wireless optical communication (UWOC) is becoming a prospective technique in marine exploration. We investigated UWOC performance using different representative structured beams. The transmission performances of the Gaussian, Bessel–Gaussian (BG), Ince–Gaussian (IG), and radially polarized Gaussian (RPG) beams were experimentally demonstrated and evaluated in underwater channels subjected to thermal gradient. The experimental results show that the BG, IG, and RPG perform better against the thermal gradient. Compared with the Gaussian beams, the beam wanders of BG, IG, and RPG beams under the thermal gradient have been reduced by 56.9%, 8.2%, and 59%, the scintillation indices have been decreased by 12.8%, 17.3%, and 28.9%, and the BER performance of the BG, IG, and RPG beams have been improved by ∼5.5, ∼3.7, and ∼5.2dB at the forward error correction threshold (FEC threshold). Based on the above results, the RPG beam is a more promising light source for UWOC. The experimental results provide a promising beam choice for UWOC.

Modulation effect of focusing mirror on beam propagation through anisotropic turbulence

In this study, we modulated the Bessel-Gaussian (BG) beam using a focusing mirror to enhance the performance of wireless optical communication (WOC) while considering the angles between turbulence cells and the transmitted direction when beams propagate through anisotropic atmospheric turbulence along a slant path. Numerical results reveal that when the BG beam is modulated by a focusing mirror with a focusing length of 1 km, the detection probability of orbital angular momentum (OAM) is increased by 9.06% compared with the unmodulated BG beam when the OAM quantum number is 1. Simultaneously, this modulation method effectively reduces the bit error rate and enhances the channel capacity in OAM-based WOC. Furthermore, we observed that the smaller the OAM number, the better the effect of the modulation. Through our analysis, we identified that the most significant distortions in OAM mode propagation occur at the exponential parameter approximately 3.1 in the modified von Karman spectrum. Moreover, we demonstrated that the effects of the anisotropic tilt angle can not be negligible for beams through a slant path. Therefore, the modulation of the focusing mirror, in combination with a well-designed propagation direction that takes appropriate angles into account, can significantly improve the overall quality and performance of optical communication systems.

Focusing characteristics of space-variant quadratic phase modulated linearly polarized Bessel–Gaussian vortex beam

Focusing characteristics of space-variant quadratic phase modulated linearly polarized Bessel–Gaussian vortex beam

Multioptical bottles from the chirped circular Bessel Gaussian beams carrying annular spiral-zone power-exponent-phase

In this paper, we introduce a new structure of multioptical bottles formed by the chirped circular Bessel Gaussian beams carrying annular spiral-zone power-exponent-phase (ASP). The ASP is a general term for complex phases composed of the radial phase, equiphase, and power spiral phase. By combining the influence of autofocusing properties, chirp factor, and ASP mode, the propagation dynamics of the proposed multioptical bottles beam such as the sizes, lengths, number and locations can be flexibly manipulated. Intriguingly, the effect of the power order of ASP mode on the beam propagation dynamics is firstly introduced and examined. The proposed beams can enable diversification the optical tweezers system in multiparticle manipulation, which is verified by the radiation force analysis on a Rayleigh particle.

Topological charges measurement of circular Bessel Gaussian beam with multiple vortex singularities via cross phase

In this paper, we firstly propose a method to measure the topological charges (TCs) of a circular Bessel Gaussian beam with multiple vortex singularities (CBGBMVS) by utilizing cross phase. Based on theory and experiment, the cross phase is utilized to realize the TCs measurement of the CBGBMVS in free space with different situations, such as different singularity number, TCs and singularity location. Especially, the TCs measurement method is also investigated and verified in atmosphere turbulence. Our work provides an effective and convenient way to realize the TCs measurement of multiple singularities embedded in abruptly autofocusing host beams which has plenty of potential application in optical communication.

Determining Topological Charge of Bessel-Gaussian Beams Using Modified Mach-Zehnder Interferometer

The orbital angular momentum (OAM) associated with structured singular beams carries vital information crucial for studying various properties and applications of light. Determining OAM through the interference of light is an efficient method. The interferogram serves as a valuable tool for analyzing the wavefront of structured beams, especially identifying the order of singularity. In this study, we propose a modified Mach–Zehnder interferometer architecture to effectively determine the topological charge of Bessel–Gaussian (BG) beams. Several numerically generated self-referenced interferograms have been used for analysis. Moreover, this study examines the propagation property and phase distribution within BG beams after they are obstructed by an aperture in the interferometer setup.

Effect of self-focusing of bessel gauss laser beam on excitation of electron plasma wave in collisionless plasma with axial density ramp

Effect of self-focusing of bessel gauss laser beam on excitation of electron plasma wave in collisionless plasma with axial density ramp

Possibility of Forming Perfect Vortices from Bessel–Gaussian Beams

Possibility of Forming Perfect Vortices from Bessel–Gaussian Beams

Propagation properties of elegant modified Bessel Gaussian beams.

A kind of optical beam with a radially parabolic propagating manner and intensity decay inversely proportional to propagating distance in the far field is investigated. The initial complex amplitudes of this kind of beam have the form of a Gaussian function multiplied by a m/2-order modified Bessel function and a helical phase factor with topological charge m. The arguments for Bessel and Gauss parts in the propagating solutions of these beams are complex and symmetric as elegant Laguerre and Hermite Gaussian beams. As a result, the beams can be referred to as elegant modified Bessel Gauss (EMBG) beams. Similar to non-diffractive beams such as Bessel and Airy beams, the EMBG beams also carry infinite power due to a transversely slowly decaying tail of complex amplitude. The EMBG beams demonstrate intermediate propagating properties between non-diffractive and finite-power beams. Unlike non-diffractive beams that never spread their power and finite-power beams that always diverge in a linear manner and spread their power by inversely square law in the far field, the EMBG beams demonstrate a far-field parabolic propagating manner and decay their power by inversely linear law. In addition, the EMBG beams have total Gouy phase, which is only half of that of elegant Laguerre Gauss beams with the same topological charge, and have far-field intensity distributions regardless of the beam waist radius in the initial plane. The propagating and focusing properties of EMBG beams represent an intermediate status between the non-diffractive and finite-power beams.

Performance evaluation of the data transmission link with Bessel-Gaussian beams through a tunable smoke channel

We simulate and experimentally demonstrate a 1 Gbps free-space optical (FSO) communication system in a smoke chamber with the Bessel–Gaussian (BG) beam. Firstly, we simulate and analyze the attenuation and bit error rate (BER) of BG and Gaussian beams in the smoke channel based on the Monte Carlo method. The results show that BG beams have more advantages than Gaussian beams in smoke transmission. Then we generate a BG beam based on the spatial light modulator (SLM) method, the BG beam’s central spot shows a stable diameter of about 0.9 mm propagating 3.2 m in space. The 1 Gbps 1550 nm on/off keying (OOK) signal is loaded on the BG beam via a bit error rate test (BERT). Next, a tunable smoke channel is established based on an acrylic chamber, and the attenuation and visibility of the smoke channel are characterized in real-time. Finally, the intensity distributions, power stability, power attenuation and BER performance of the BG and Gaussian beams’ transmission links in the tunable smoke channel are investigated. The experimental results show the improvements in transmission performance under the smoke channel conditions using BG beams. Compared with Gaussian beams, BG beams exhibit lower power attenuation (reduced by up to 3.13 dB) and a more stable receiver (decreased by 23 % in standard deviation). Additionally, the BER of 1 Gbps of the transmission link with the BG beam improved by 7.18 dB–10.17 dB in the tunable smoke channel (0.5–2 m). As the length of the smoke channel increases, the improvement of the BG beam in the smoke channel increases as well. The BG beam has shown remarkable advantages in transmission links through the smoke channel. The research offers a robust and generalized proposal for FSO communications based on structured beams.