Generation Of Airy Beams Research Articles

Phase-modulated Airy beam generation by a leaky-wave structure

Phase-modulated Airy beam generation by a leaky-wave structure

Experimental analysis of Airy beam self-localization in nematic liquid crystals.

This study employs experimental demonstration of finite energy Airy beam (AB) propagation in nematic liquid crystals (NLCs), highlighting the reorientational optical nonlinearity that induces the generation of off-shoot solitons (OSS). The outcomes of our investigation indicate that the direction of the OSS is greatly influenced by optical power and the beam's walk-off, providing novel perspectives on light manipulation in NLCs. These findings significantly advance understanding Airy beam behavior in nonlinear materials and propose potential applications in photonic tools.

Highly efficient Airy beam generator with high polarization purity by a receiving-transmitting metasurface

This paper presents a highly efficient Airy beam generator at microwave frequency using a transparent metasurface with a receiving-transmitting scheme. The amplitude and phase of the transmitted orthogonal polarization wave can be flexibly controlled by orientation angles of receiving and transmitting patches of the proposed meta-atom. Utilizing this property to reshape the field of transmitted waves following the desired phase and amplitude profile of the Airy wave packet, an Airy beam generator is designed and experimentally demonstrated. Simulation and measurement results both show a self-healing Airy beam with an efficiency of 23.5% and polarization purity above 20 dB, which approaches the theoretical limitation of the designed Airy beam. Due to the well-performed beam efficiency and polarization purity resulting from the receiving-transmitting metasurface, our design holds great promise for efficient wavefront shaping and facilitates the use of high-purity Airy beams for practical applications.

Interference‐Assisted Independent Amplitude and Phase Manipulation with Broadband Chiral Meta‐Mirror

AbstractAchieving simultaneous amplitude and phase control is crucial in various spin‐selective optical applications, particularly for chiral mirrors that exhibit distinct responses when illuminated by orthogonal circularly polarized waves. However, conventional chiral metasurface approaches for amplitude manipulation can only be implemented by adjusting absorption, which limits the bandwidth due to the dispersion nature of the meta‐structure and cannot ensure that the chiral mirror output only one circular polarization component with independent amplitude and phase manipulation at multi‐polarization incidence. Here, an interference‐mechanism‐assisted methodology is proposed for broadband chiral meta‐mirrors with independent control over amplitude and phase. Such controls are achieved by simply setting the rotation angle of each meta‐atom in the integrated quad‐atom structure. The rotation angle of each meta‐atom and the difference between adjacent meta‐atoms rotation angles provide flexible degrees of freedom for controlling phase and amplitude, respectively. Notably, this mechanism stemming from the Pancharatnam‐Berry phase allows for wideband operation due to its dispersion‐free nature of phase control. As proof‐of‐principle demonstrations, numerically verify a series of amplitude‐tailorable phase‐gradient meta‐mirrors and experimentally demonstrate a broadband chiral Airy beam generator. This method offers a straightforward solution for spin‐selective amplitude/phase manipulation which may have the potential to advance the engineering application of chiral metasurfaces.

Terahertz generation of Airy beam with polarization conversion in a reflective vanadium dioxide metasurface

Airy beam possesses a wide range of applications owing to its special properties of non-diffraction, self-accelerating, and self-healing. However, conventional Airy beam generators are not conducive to their miniaturization or integration. In this paper, a technique for generating Airy beam is introduced with polarization conversion within the frequency range of 0.9–1.2 THz based on a reflective vanadium dioxide (VO2) metasurface. Our design is composed of VO2 elliptical patch, SiO2 spacer, and gold substrate. When the metallic VO2 is involved, the proposed metasurface can efficiently generate cross-polarized Airy beam since amplitude and phase distributions of reflected wave are modulated simultaneously by rotating tilt angle of each VO2 patch. Conversely, when the insulating VO2 is involved, the metasurface does not generate Airy beam. In addition, we demonstrate broadband effect and autofocusing phenomenon of the metasurface. The proposed Airy beam generator may be of great interest for beam shaping, biomedical imaging, and laser fabrication.

Fiber end integrated surface plasma lens for circular airy beam shaping

This paper presents a circular Airy beam generator based on a fiber end integrated surface plasma lens. The surface plasma lens consists of a nano-annular slot and an array of series concentric circular grooves etched on the gold film coated on the fiber end. When the fiber light field illuminates the nano-annular slot, surface plasmon polaritons (SPPs) will be excited, then the SPPs propagates along the surface of the gold film, and will finally be decoupled into free space to generate circular Airy beam by the array of concentric circular grooves. The effect of the parameters of the plasma lens on the properties of the output circular Airy beam, such as self-focusing, focal spot size, is studied in detail via FDTD simulations. In addition, we found that the proposed plasma lens has a high tolerance to manufacturing errors. The case that instead of the nano-annular slit with a circular wheat-spike shaped structure is also investigated. In this case, due to the different photon spin response of the circular wheat-spike shaped structure, the device can generate circular Airy beam when the input fiber light field is right-handed circularly polarized (RHCP) light, and subwavelength Bessel-like nondiffracting beam when the input fiber light field is left-handed circularly polarized (LHCP) light. These results provide a highly integrated all-fiber circular Airy beam and subwavelength Bessel-like nondiffracting beam generation scheme, which may be useful in the areas of fiber end structured light beam shaping and fiber-integrated photonic devices.

Complex-Amplitude Programmable Versatile Metasurface Platform Driven by Guided Wave.

Metasurfaces have shown unparalleled controllability of electromagnetic (EM) waves. However, most of the metasurfaces need external spatial feeding sources, which renders practical implementation quite challenging. Here, a low-profile programmable metasurface with 0.05λ0 thickness driven by guided waves is proposed to achieve dynamic control of both amplitude and phase simultaneously. The metasurface is fed by a guided wave traveling in a substrate-integrated waveguide, avoiding external spatial sources and complex power divider networks. By manipulating the state of the p-i-n diodes embedded in each meta-atom, the proposed metasurface enables 1-bit amplitude switching between radiating and nonradiating states, as well as a 1-bit phase switching between 0° and 180°. As a proof of concept, two advanced functionalities, namely, low sidelobe-level beam scanning and Airy beam generation, are experimentally demonstrated with a single platform operating in the far- and near-field respectively. Such complex-amplitude, programmable, and low-profile metasurfaces can overcome integration limitations of traditional metasurfaces, and open up new avenues for more accurate and advanced EM wave control within an unprecedented degree of freedom.

The Effect of B-Integral on the Propagation of the Annular Array Airy Beam

The Effect of B-Integral on the Propagation of the Annular Array Airy Beam

Generating Airy beams through multimode fibres.

Focussing light through a multimode fibre (MMF) is the basis of holographic endoscopes, which currently enable detailed imaging of deep tissue. Achieving high fidelity and purity diffraction-limited foci has been shown to be possible, when fully controlling the amplitude, phase, and two orthogonal polarisation states of the input field. Yet, generating more complex field distributions with similar performance remains to be assessed. Here, we demonstrate the generation of Airy beams through an MMF containing in excess of 90 % of the optical power delivered by the fibre. We discuss two distinct methods for generating optical landscapes: the direct field and the Fourier domain synthesis. Moreover, we showcase the flexibility of the Fourier domain synthesis to modify the generated beam.

Temporal behavior of diffusion-trapped Airy beams in photorefractive media

We theoretically examine the temporal behavior of novel Airy beams, their interactions, and their dependence on thermal energy associated with diffusive nonlinearity in photorefractive media. For the first time, it is examined under the time-dependent diffusive-saturable nonlinear Schrödinger equation (DSNLSE). The results show that optical Airy beam propagation is effectively controlled by illumination time. In long propagation distance, the significant illumination time of the thermal energy-independent optical Airy beams associated with diffusive nonlinearity lead to unstable self-deflection soliton beams over the increasingly intense competition between photorefractive nonlinearity and diffusive nonlinearity. Meanwhile, in short propagation distance, optical Airy beams were found to maintain their acceleration over a certain distance as time increased. The temporal behavior of the interaction of optical Airy beams shows that in phase, they are affected by illumination time, while out of phase, they show almost no significant changes. We find that fusion solitons eventually emerge in phases. On the other hand, we also find that this self-trapped wave packets self-bend during propagation with an acceleration rate that depends on the thermal energy associated with diffusive nonlinearity. Finally, we found that the study results agreed well with previous experiments and studies.

Full Complex-Amplitude Modulation of Surface Waves Based on Spin-Decoupled Metasurface.

This work proposes a method for surface wave (SW) coupling along with flexible complex amplitude modulation of its wavefront. The linearly polarized incident plane wave is coupled into the surface mode with complex wavefront by exploiting the spin-decouple nature of a reflective chiral meta-atom. As verification, two kinds of metasurface couplers are designed. The first kind contains two examples for SW airy beam generation with and without deflection under linearly polarized illumination, respectively. The second kind is a bi-functional device capable of SW focusing under left-handed circularly polarized illumination, and propagating wave deflection under right-handed circularly polarized illumination, respectively, to verify the fundamental spin-decoupled character. Simulated and experimental results are in good agreement. We believe that this method provides a flexible approach for complex SW applications in integrated optics, optical sensing, and other related fields.

Arbitrary Optical Wavefront Shaping with Holographic Plasmonic Gap Waveguides

AbstractManipulations of free‐space light are usually achieved through various metasurfaces and spatial light modulators. However, an external light source is required to excite these devices, making complete on‐chip integrations difficult. Integrated photonics enables the miniaturization and multi‐functionalization of optical systems by densely packing numerous optical components on a single chip. Particularly, plasmons have recently attracted extensive attention due to their unique abilities to enable the routing and manipulation of light at the nanoscale. Here optical wavefront shaping achieved by holographic metal‐insulator‐metal plasmonic gap waveguides is reported. An arbitrary free‐space wave's amplitude and phase information can be recorded in the waveguide by the amplitude variation of the guided wave. By elaborately designing the plasmonic gap waveguide, the guided waves can be molded into any desired free‐space light field, thus enabling complex free‐space functions including highly directional beams, dual beams with arbitrarily tailorable power ratio and radiation angles, focusing beams, and Airy beam generation. This study opens a new route for optical wavefront shaping via modulating guided waves. It paves the way for optical interconnects across multifunctional photonic integrated devices and free space, holding potential in optical communications, light detection and ranging, imaging, and displays.

Generation and regulation of two-dimensional autofocusing Airy beams based on holographic metasurfaces

This paper proposes a new method to generate a two-dimensional (2D) Airy beam and Airy autofocusing beam by using the scalar holographic metasurface with amplitude-phase modulation in the microwave band. The proposed holographic metasurface comprises subwavelength patch unit cells with a period of fewer than 1/8 wavelengths, which means that it has the finer sampling for electromagnetic waves and can simultaneously achieve precise modulations for the amplitude and phase of electromagnetic waves. Firstly, the 2D-Airy beam with quasi-non-diffraction and self-bending characteristics is generated, from which the holographic metasurface is designed to realize four different 2D-Airy beams with the same focus, achieving the 2D-Airy autofocusing beam in the microwave frequency. The holographic metasurface for Airy beam generation has high efficiency and an ultra-lower profile. Meanwhile, for applying the Airy beam in wireless power transfer (WPT), the efficiency of the generated Airy beam and Airy autofocusing beam is calculated for the first time in the microwave field. The simulation results show that the efficiency of the 2D-Airy beam can reach 66% at 150 ​mm away from the metasurface, while the efficiency of the 2D-Airy autofocusing beam at the focus, which is 280 ​mm from the metasurface, can reach 35%. The theoretical, simulated, and measured results show that the proposed method and holographic metasurfaces can flexibly achieve the special characteristics of self-autofocusing and self-bending Airy beams in the microwave domain, providing an effective path for wireless power transfer (WPT) scenario with radial obstructions.

Generation of broadband non-diffraction millimeter-wave airy beams based on high-efficiency tri-layer metasurfaces

Airy beams based on the Airy function, exhibiting a special curved parabolic trajectory, can effectively alleviate diffraction along its propagation and hold potential in many interesting applications. However, to date, the broadband and high-efficiency generation of non-diffraction Airy beams has remained largely unexplored, especially in the millimeter-wave range that is full of great application potential. In this paper, broadband 1-D and 2-D Airy beam generators utilizing high-efficiency tri-layer metasurfaces operating from 55 to 67 GHz are presented. The metasurfaces consist of elaborately tailored meta-atoms that can independently realize complete amplitude modulation from 1% to 98% and binary phase tuning of 0 and π. The Airy beam generators are engineered and verified by simulations and experiments, which demonstrate the broadband quasi-non-diffraction feature and curved trajectory of the Airy beam. Compared to the 1-D Airy beam generator, the measured quasi-non-diffraction propagation property of the 2-D Airy beam can be maintained by greater than 160 free-space wavelengths across the entire bandwidth. Self-reconstruction property of the 2-D Airy beam is also experimentally validated in the presence of metallic and dielectric obstacles. This work may benefit novel applications of Airy beams in millimeter-wave imaging and detection.

Generation of nonlinear Airy beams with switchable acceleration direction

Airy beams, which propagate along a curved trajectory, have been widely utilized in optical tweezers, biomedical analysis, and material processing. However, the dynamic regulation of nonlinear Airy beams is still challenging. Here, we demonstrate directionally switchable nonlinear Airy beams via three-dimensional (3D) nonlinear photonic crystals (NPCs) fabricated by the femtosecond laser erasing technique. The 3D NPCs contain several sequential arrays of spatially modulated nonlinearities with different spatial frequencies and cubic coefficients. By tuning the wavelength of the fundamental beam, the quasi-phase-matching condition can be switched to modulate the acceleration direction and wavelength of the generated nonlinear Airy beam. This offers a versatile platform for dynamic nonlinear Airy beam generation, paving the way for applications in optical trapping, optical communication, and biomedical imaging.

Generation and Manipulation of Airy Breathing Solitons in an Inhomogeneous Medium with Periodic Potential

The propagation characteristics of Airy beams in an inhomogeneous medium with periodic potential are studied theoretically and numerically. The Gross–Pitaevskii equation was solved with periodic potential using the separating variables method, and a breathing soliton solution and the breathing period were obtained. Further, the propagation properties of an Airy beam, and the interaction between two Airy beams while considering the medium parameters and beam parameters were numerically simulated in detail. First, we discuss the influence of the initial medium parameters (modulation intensity P and modulation frequency ω) on the propagation characteristics. Then, we investigate the effect of the initial beam parameters (initial chirp C and position x0) on the propagation characteristics. Lastly, the interaction of two Airy beams with opposite spatial positions for different phase φ, amplitude A, and initial interval x0 is analyzed. The breathing period and central position of the breathing solitons could be controlled by changing the initial medium parameters. By varying the initial beam parameters, the deflection direction and size, and the maximal intensity of the breathing solitons were manipulated. The breathing solitons of different bound states were formed by changing the phase φ, amplitude A, and initial interval x0 of two Airy beams. The results provide a theoretical basis for the propagation and manipulation of Airy beams.

Propagation of Airy beams in uniformly accelerated space

Airy beams are a kind of non-diffracting beams and so-called accelerating beams with great potential applications in many fields recently. In this work, we investigate the self-accelerating characteristics and the self-healing abilities of Airy beams in uniformly accelerated space. It shows that the process of the Airy beams propagating in accelerated space will be speed up for the positive acceleration or slow down for the negative acceleration. The result may be useful to explore the behavior of light in different accelerated space.

Numerical Simulation of Integrated Generation and Shaping of Airy and Bessel Vortex Beams Based on All-Dielectric Metasurface

Integrating multiple independent functions into a single optical component is one of the most important topics in research on photoelectric systems. In this paper, we propose a multifunctional all-dielectric metasurface that can achieve a variety of non-diffractive beams depending on the polarization state of the incident light. Using the anisotropic TiO2 rectangular column as the unit structure, the three functions of generating polygonal Bessel vortex beams under left-handed circularly polarized incidence, Airy vortex beams under right-handed circularly polarized incidence and polygonal Airy vortex-like beams under linearly polarized incidence are realized. In addition, the number of polygonal beam sides and the position of focal plane can be adjusted. The device could facilitate further developments in scaling complex integrated optical systems and fabricating efficient multifunctional components.

Complex-amplitude modulation of surface waves based on a metasurface coupler.

Simultaneous and independent modulation of the amplitude and phase of surface waves (SWs) is critical in photonics and plasmonics. Here, we propose a method for flexible complex-amplitude modulation of SWs based on a metasurface coupler. Benefiting from the full range complex-amplitude modulation ability of the meta-atoms over the transmitted field, the coupler can convert the incident wave into a driven surface wave (DSW) with an arbitrary combination of amplitude and initial phase. By placing a dielectric waveguide that supports guided SWs below the coupler, the DSWs can resonantly couple to SWs while preserving complex-amplitude modulation. The proposed scheme provides a practical way for freely tailoring the phase and amplitude profiles of SWs wavefronts. As verification, meta-devices for normal and deflected SW Airy beam generation and SW dual focusing are designed and characterized in the microwave regime. Our findings may stimulate various advanced surface optical meta-devices.

3D single shot lensless incoherent optical imaging using coded phase aperture system with point response of scattered airy beams

Interferenceless coded aperture correlation holography (I-COACH) techniques have revolutionized the field of incoherent imaging, offering multidimensional imaging capabilities with a high temporal resolution in a simple optical configuration and at a low cost. The I-COACH method uses phase modulators (PMs) between the object and the image sensor, which encode the 3D location information of a point into a unique spatial intensity distribution. The system usually requires a one-time calibration procedure in which the point spread functions (PSFs) at different depths and/or wavelengths are recorded. When an object is recorded under identical conditions as the PSF, the multidimensional image of the object is reconstructed by processing the object intensity with the PSFs. In the previous versions of I-COACH, the PM mapped every object point to a scattered intensity distribution or random dot array pattern. The scattered intensity distribution results in a low SNR compared to a direct imaging system due to optical power dilution. Due to the limited focal depth, the dot pattern reduces the imaging resolution beyond the depth of focus if further multiplexing of phase masks is not performed. In this study, I-COACH has been realized using a PM that maps every object point into a sparse random array of Airy beams. Airy beams during propagation exhibit a relatively high focal depth with sharp intensity maxima that shift laterally following a curved path in 3D space. Therefore, sparse, randomly distributed diverse Airy beams exhibit random shifts with respect to one another during propagation, generating unique intensity distributions at different distances while retaining optical power concentrations in small areas on the detector. The phase-only mask displayed on the modulator was designed by random phase multiplexing of Airy beam generators. The simulation and experimental results obtained for the proposed method are significantly better in SNR than in the previous versions of I-COACH.