Optical Airy Beams Research Articles

Spectrum conversion and pattern preservation of Airy beams in fractional systems with a dynamical harmonic-oscillator potential

We investigate the dynamics of optical Airy beams in the one-dimensional fractional Schrödinger equation with a harmonic-oscillator (HO) potential subjected to modulation along the propagation distance. Deriving general solutions for propagating beams and particular solutions for Airy waves with/without chirp, we study analytically the spectrum conversion and pattern preservation for the chirp-free and chirped Airy beams in the fractional system including the HO potential with moiré-lattice, hyperbolic-secant, and delta-functional modulation formats. For the HO-moiré-lattice potential, it is found that the chirp-free Airy beam experiences multiple spectrum conversions between the Airy and Gaussian patterns in the momentum space, preserving the Airy pattern in the coordinate space. The chirp magnitude of the chirped Airy beam determines whether the spectrum conversion occurs in the momentum space, and the splitting and evolution direction of the beam in the coordinate space. For the HO-hyperbolic-secant potential, the chirp-free Airy beam undergoes spectrum conversion and tunneling, with the positions of the spectrum conversion and tunneling significantly depending on parameters of the hyperbolic-secant potential; however, the spectrum conversion and pattern preservation of the chirped Airy beam occurs only under a certain relation of the chirp and parameters of the potential. In the case of the HO-delta-functional potential, the chirp-free Airy beam experiences abrupt spectrum conversion and a two-step spectrum shift; however, for the chirped Airy beam, the spectrum conversion is affected by the relation between the chirp and height of the potential. Effects of the fractional Lévy index on the spectrum conversion and pattern preservation of the Airy beams under the action of the three modulation patterns considered here are also explored in detail.

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.

Generation and characteristics of an Airy vortex beam from the anomalous vortex beam

Hybrid beams have evoked a long-running research upsurge due to its unique properties and extensive application. In this paper, we propose a novel method to generate a kind of hybrid Airy vortex beam (AiVB) with orbital angular momentum (OAM) by imposing a phase modulation on an anomalous vortex beam (AVB), which hybrid AiVB possesses dual characteristics of both optical vortices and Airy beams. According to the integral formula of Airy transform, analytical formula of the AiVB generated from the incident AVB via an optical Airy transform system (OATS) is derived. Eenergy flux density and OAM density of the AiVBs are investigated based on the Maxwell equation and Lorentz force formula, and four representative modes (E11, E12, E13, E14) of the AiVB are selected to elucidated graphically. In addition, dependence of the normalized intensity distribution, OAM density distribution, phase variation, and electric field’s gradient vector of the generated AiVBs on the control parameters δ0x and δ0y of the OATS and topological charge m are also considered. Results obtained here would further enrich the research on the vortex beams and provide theoretical basis for producing versatile optical vortices.

Generation and deflection control of a 2D Airy beam utilizing metasurfaces.

Self-accelerating optical Airy beams present attractive characteristics such as self-bending and non-diffraction, which have rendered this field a research hotspot in recent years. In this paper, the desired phase changes of the unit cell structure for the transmitted cross-polarized wave can be realized by modifying the rotation angle of the unit cell, while the amplitude can be modulated by changing the inner diameter R of the double layer split-ring resonator (SRR). As such, the amplitude and phase modulations can be performed simultaneously and independently to achieve the desired transmitted wave envelope. Furthermore, a novel, to the best of our knowledge, strategy of 2D Airy beam deflection control is also presented by simultaneously modifying the phase and amplitude of the envelope of the transmitted beam, and its feasibility is theoretically and experimentally demonstrated. Our proposed designs suggest high application potentials in the fields of optical particle manipulation, controllable wireless energy transmission, and complex terrain exploration.

Compact broadband silicon-integrated Airy beam emitter.

Optical Airy beams have wide-ranging applications in photonics, but conventional approaches for generating Airy beams require bulky and strictly aligned optical systems. Here, we propose on-chip compact Airy beam emitters by using a shallow-etched holography grating on a silicon platform. The holography grating, formed by the binary interferogram of the guided wave and the spatial Airy beam, can scatter the guided waves into spatial waves with the phase distributions being consistent with those of Airy beam. The simulation demonstrates that a 20µm×20µm holography grating on a strip waveguide enables the realization of 2D Airy beam within the wavelength range from 1490 to 1570 nm. Our results suggest a promising avenue towards potential applications in on-chip imaging, optical forces, optical interconnection, etc.

1D Self-Healing Beams in Integrated Silicon Photonics

Since the first experimental observation of optical Airy beams, various applications ranging from particle and cell micromanipulation to laser micromachining have exploited their non-diffracting and accelerating properties. The later discovery that Airy beams can self-heal after being blocked by an obstacle further proved their robustness to propagate under scattering and disordered environment. Here, we report the generation of Airy beams on an integrated silicon photonic chip and demonstrate that the on-chip 1D Airy beams preserve the same properties as the 2D beams. The 1D meta-optics used to create the Airy beam has the size of only 3 by 16 microns, at least three orders of magnitude smaller than the conventional optic. The on-chip self-healing beams demonstrated here could potentially enable diffraction-free light routing for on-chip optical networks and high-precision micromanipulation of bio-molecules on an integrated photonic chip.

Manifestation of a highly sensitive evanescent wave absorption-based refractive index sensor realized by radiating with an optical Airy beam

In this research, a theoretical perception on the notion of an ultra-high sensitive evanescent wave-based fiber-optic refractive index sensor has been proposed by shining an optical Airy beam. The sensing configuration consists of a multimode fiber which is decladded from the middle to aptly sculpt the evanescent wave. In presence of the Airy beam, effectual coupling of high-order modes within the sensing structure has been affirmed by using the classical wave-optic model. To corroborate our theoretical study, an Eigenmode expansion solver (EME) propagation analysis was conducted in commercially offered Mode solution software (Lumerical Inc.) to investigate the transmission characteristics of Airy beam within the waveguide structure. Compared with conventional Gaussian beam-based sensor, the proposed refractive index sensor renders a maximum 19.15 fold superior sensitivity of 992.39 dB/RIU with an admirable sensing resolution of ∼1.00 × 10−5 RIU. Thus, this nascent-class of beam called Airy beam manifests a new degree of freedom which demonstrates the viability of the proposed scheme for the usage of chemical and biological sensing.

Atomically Thin Nonlinear Transition Metal Dichalcogenide Holograms.

Nonlinear holography enables optical beam generation and holographic image reconstruction at new frequencies other than the excitation fundamental frequency, providing pathways toward unprecedented applications in optical information processing and data security. So far, plasmonic metasurfaces with the thickness of tens of nanometers have been mostly adopted for realizing nonlinear holograms with the potential of on-chip integration but suffering from low conversion efficiency and high absorption loss. Here, we report a nonlinear transition metal dichalcogenide (TMD) hologram with high conversion efficiency and atomic thickness made of only single nanopatterned tungsten disulfide (WS2) monolayer, for producing optical vortex beams and Airy beams as well as reconstructing complex holographic images at the second harmonic (SH) frequency. Our concept of nonlinear TMD holograms paves the way toward not only the understanding of light-matter interactions at the atomic level but the integration of functional TMD-based devices with atomic thickness into the next-generation photonic circuits for optical communication, high-density optical data storage, and information security.

Recovery time of matter Airy beams using the path integral quantum trajectory model

Abstract Following their discovery in the late 1970s, optical Airy beams have found numerous applications in technologies such as microscopy and optical trapping, many of which are based on the wave packets’ unique features such as zero or minimal diffraction, self-acceleration, and self-healing. Recent advancements have shown that Airy beams can also be produced using matter waves with many of the same unique characteristics of their optical counterparts. We present here a study of the recovery time of damaged matter Airy wave packets in free space and a nonlinear Kerr-type medium. We show that in free space the recovery time increases approximately linearly with mass and is independent of other kinematical parameters such as momentum, velocity, and spatial width. In the Kerr-type medium, recovery time is decreased compared to free space and does not scale linearly with mass. In order to study matter Airy beams, we introduce the Path Integral Quantum Trajectory model as a new computational tool for the study of non-relativistic, quantum mechanical wave packets and demonstrate its effectiveness in dealing with heavy particle dynamics.

Quantum Airy photons

With exotic propagation properties, optical Airy beams have been well studied for innovative applications in communications, biomedical imaging, micromachining, and so on. Here we extend those studies to the quantum domain, creating quantum correlated photons in finite-energy Airy transverse modes via spontaneous parametric down conversion and subsequential spatial light modulation. Through two-photon coincidence measurements, we verify their Airy spatial wavefunctions, propagation along a parabolic trajectory, and that the spatial modulation does not introduce any observable degradation of quantum correlation between the photons. These results suggest the feasibility of using spatially structured photons for practically advantageous quantum applications.

Vortex Airy beams directly generated via liquid crystal q-Airy-plates

Liquid crystal q-Airy-plates with director distributions integrated by q-plates and polarization Airy masks are proposed and demonstrated via the photoalignment technique. Single/dual vortex Airy beams of opposite topological charges and orthogonal circular polarizations are directly generated with polarization-controllable characteristic. The singular phase of the vortex part is verified by both astigmatic transformation and digital holography. The trajectory of vortex Airy beams is investigated, manifesting separate propagation dynamics of optical vortices and Airy beams. Meanwhile, Airy beams still keep their intrinsic transverse acceleration, self-healing, and nondiffraction features. This work provides a versatile candidate for generating high-quality vortex Airy beams.

Three-dimensional ultrashort optical Airy beams in an inhomogeneous medium with carbon nanotubes

In this Letter, we consider the problem of the dynamics of propagation of three-dimensional optical pulses (a.k.a. light bullets) with an Airy profile through a heterogeneous environment of carbon nanotubes. We show numerically that such beams exhibit sustained and stable propagation. Moreover, we demonstrate that by varying the density modulation period of the carbon nanotubes one can indirectly control the pulse velocity, which is a particularly valuable feature for the design and manufacturing of novel pulse delay devices.

Airy beam self-focusing in a photorefractive medium.

The unique bending and shape-preserving properties of optical Airy beams offer a large range of applications in for example beam routing, optical waveguiding, particle manipulation and plasmonics. In these applications and others, the Airy beam may experience nonlinear light-matter interactions which in turn modify the Airy beam properties and propagation. A well-known example is light self-focusing that leads to the formation of spatial soliton. Here, we unveil experimentally the self-focusing properties of a 1D-Airy beam in a photorefractive crystal under focusing conditions. The transient evolution involves both self-bending and acceleration of the initially launched Airy beam due to the onset of an off-shooting soliton and the resulting nonlocal refractive index perturbation. Both the transient and stationary self-focusing properties can be tuned by varying the bias electric field, the injected Airy beam power and the background illumination.

Generation of self-healing and transverse accelerating optical vortices

Self-healing and transverse accelerating optical vortices are generated via modulating Gaussian beams through subsequent liquid crystal q-plate and polarization Airy mask. We analyze the propagation dynamics of these vortex Airy beams, and find that they possess the features of both optical vortices and Airy beams. Topological charges and characteristics of nondiffraction, self-healing, and transverse acceleration are experimentally verified. In addition, vortex Airy beams with both topological charge and radial index are demonstrated and mode switch among Gaussian, vortex, vector, Airy beams and their combinations can be acquired easily. Our design provides a flexible and highly efficient way to generate unique optical vortices with self-healing and transverse acceleration properties, and facilitates prospective applications in optics and photonics.

Creating Airy beams employing a transmissive spatial light modulator.

We present a detailed study of two novel methods for shaping the light optical wavefront by employing a transmissive spatial light modulator (SLM). Conventionally, optical Airy beams are created by employing SLMs in the so-called all-phase mode. In the first method, a numerically simulated lens phase distribution is loaded directly onto the SLM, together with the cubic phase distribution. An Airy beam is generated at the focal plane of the numerical lens. We provide for the first time, to the best of our knowledge, quantitative properties of the formed Airy beam. We derive the formula for deflection of the intensity maximum of the so-formed Airy beam, which is different from the quadratic deflection typical of Airy beams. We cross-validate the derived formula by both simulations and experiment. The second method is based on the fact that a system consisting of a transmissive SLM sandwiched between two polarizers can create a transmission function with negative values. This observation alone has the potential for various other wavefront modulations where the transmission function requires negative values. As an example for this method, we demonstrate that a wavefront can be modulated by passing the SLM system with transmission function with negative values by loading an Airy function distribution directly onto the SLM. Since the Airy function is a real-valued function but also with negative values, an Airy beam can be generated by direct transfer of the Airy function distribution onto such an SLM system. In this way, an Airy beam is generated immediately behind the SLM. As both new methods do not employ a physical lens, the two setups are more compact than conventional setups for creating Airy beams. We compare the performance of the two novel methods and the properties of the created Airy beams.

Airy-like electron plasma wave

In this paper, an Airy-like electron plasma wave is investigated in an unmagnetized collisionless plasma consisting of inertial electrons and static ions. Just like the optical Airy beam, the Airy-like electron plasma wave also has two interesting propagation characteristics: it has transverse acceleration and is diffraction-free, which display that the Airy-like electron plasma wave propagates along a curved trajectory and retains the basic structure for longer distances in the propagation direction, respectively. We give a numerical simulation for the electrostatic potential of the Airy-like electron plasma wave and show that, with the increase of the propagation distance, the electrostatic potential decreases in the propagation direction but increases in the transverse direction.

Investigating the self-healing property of an optical Airy beam.

We report the theoretical and experimental study of the self-healing property of an Airy beam related to its phase. We find that, even when the phase of an Airy beam is not preserved, the beam still exhibits the self-healing property but undergoes a severe diffraction. To decrease the diffraction effect, we utilize an electromagnetically induced transparency (EIT) image-cloning system based on position selective absorption effect to further demonstrate the self-healing phenomenon. Our experimental results show excellent agreement with the theoretical analysis.

Super-Airy beam: self-accelerating beam with intensified main lobe.

We introduce, theoretically and experimentally, the concept of a diffraction-free "super-Airy" beam, in which the main lobe is reduced to nearly half in size with increased intensity in comparison to the main lobe of the optical Airy beam, while maintaining the same transverse acceleration. It is also observed that when the super-Airy main lobe is blocked during propagation, it recovers to the original size faster than the Airy main lobe.

Curved singular beams for three-dimensional particle manipulation.

For decades, singular beams carrying angular momentum have been a topic of considerable interest. Their intriguing applications are ubiquitous in a variety of fields, ranging from optical manipulation to photon entanglement, and from microscopy and coronagraphy to free-space communications, detection of rotating black holes, and even relativistic electrons and strong-field physics. In most applications, however, singular beams travel naturally along a straight line, expanding during linear propagation or breaking up in nonlinear media. Here, we design and demonstrate diffraction-resisting singular beams that travel along arbitrary trajectories in space. These curved beams not only maintain an invariant dark “hole” in the center but also preserve their angular momentum, exhibiting combined features of optical vortex, Bessel, and Airy beams. Furthermore, we observe three-dimensional spiraling of microparticles driven by such fine-shaped dynamical beams. Our findings may open up new avenues for shaped light in various applications.

Holographic Reconstruction of Finite Airy Beams with Self-Healed and Multiplexed Features

To generate finite-power Airy beams, a novel holographic method is proposed. We record the interference pattern between an Airy beam (signal beam) and plane wave (reference beam) on a photopolymer, then decode the hologram by illuminating with the reference beam. The reconstructed beams still present the non-diffraction, acceleration, and self-healing features of optical Airy beams. In addition, angular multiplexing of two Airy beams with opposite acceleration directions is presented.