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The generation of vector beams using metasurfaces is crucial for the manipulation of light fields and has significant application potential, ranging from classical physics to quantum science. This paper introduces a novel dielectric metasurface composed of quarter-wave plate (QWP) meta-atoms, known as a QWP metasurface, designed to generate focused vector beams (VBs) of Bell-like states under right circularly polarized illumination. The propagation phase imparted on both the co- and cross-polarized components of the output field constructs hyperbolic and helical phase profiles with topological charge l p, whereas the Pancharatnam–Berry (PB) phase acts only on the cross-polarized component to construct another helical phase profile with topological charge l g. Thus, the co- and cross-polarized components form two orthogonal vector vortex (VV) modes with topological charges l p and l p + l g, respectively. When the parameter conditions are satisfied by matching the incident polarization chirality σ and topological charges l p and l g, the focused VBs of Bell-like states are generated by simultaneously manipulating the two VV modes, in contrast to existing QWP metasurfaces. The polarization states of the generated VBs are manipulated using the initial orientation angle θ 0 of the meta-atom. Overall, this research provides an innovative strategy for metasurface design, enhancing the functionality of metasurface devices for a broader range of application scenarios.

Perfect vortices, whose ring profile is independent of the topological charge, play a key role in telecommunications and particle micro-manipulation. In this work, we report the compact generation of a new kind of double-ring perfect vortices, called double-ring perfect vector beams, by exploiting dual-functional silicon metaoptics. In particular, we develop and test a new paradigm to generate those beams with the possibility of selecting different topological charges between the two rings. The generated beams are characterized through a filtering method, proving that the two rings have a vectorial nature with the same magnitude and either the same or different topological charges. Their unique properties suggest promising applications for optical tweezing and manipulation of low refractive-index particles, trapping of cold atoms, and high-capacity communications.

In this manuscript, we put forward two new types of structured light beams, the vortex Pearcey–Gauss (VPeG) beam, with a homogeneous polarisation distribution, and the vector VPeG (VVPeG) beam, with a non-homogeneous polarisation distribution. The latter is generated as a non-separable superposition of the spatial and polarisation degrees of freedom of light. We achieve their experimental realization through the combination of a spatial light modulator, which creates a scalar Pearcey–Gauss beam, and a q -plate which transforms it into a vortex or a vortex vector beam, depending on its input polarisation state. Their intensity and polarisation distributions along the propagation direction were determined through Stokes polarimetry, which was compared with numerical simulations. As demonstrated, the VVPeG beam evolves from an all-linear polarisation distribution to an approximately full Poincaré beam. The proposed vector beams add to the extensive family of non-separable states of light. We anticipate that both types of beams will find applications in fields as diverse as optical metrology and tweezers, amongst others.

In this paper, we demonstrate the capabilities of the terahertz pulse time-domain holography in visualisation, simulation, and assessment of broadband THz vortex beam formation dynamics upon its shaping by elements of beam converter, and further propagation and manipulation. By adding Jones matrix formalism to describe broadband optical elements, we highlight the differences in the spatio-spectral and spatio-temporal structure of the formed vortex and vector beams dependence on the modulator used and visualise their modal features. The influence of diffraction field structure from each element in the broadband vortex modulator is revealed in numerical simulation and the formed beams are analysed against the simplified Laguerre-Gaussian beam model.

In this paper, we review the existing approaches for vortex and vector beam shaping and generation in the terahertz frequency range. The particular focus of this review is on the possibility of homogeneous topological charge formation in the ultra-wide spectral interval inherent to ultrashort terahertz pulses. We review the available materials and components, analyse proposed and potentially possible solutions for broadband terahertz vortex and vector beam shaping, compare all developed approaches, and put forward a unified concept for constructing passive shapers of such beams from the existing component base.

We study the sharp focusing of the input structured light field that has a non-uniform elliptical polarization: the parameters of the ellipse depend on the position in the input plane (we limited ourselves to the dependence only on the angular variable). Two types of non-uniformity were considered. The first type corresponds to the situation when the semi-axes of the polarization ellipse are fixed while the slope of the major semi-axis changes. The second type is determined by the situation when the slope of the major semi-axis of the polarization ellipse is constant, and the ratio between the semi-axis changes (we limited ourselves to the trigonometric dependence of this ratio on the polar angle). Theoretical and numerical calculations show that in the case of the first type of non-uniformity, if the tilt angle is a multiple of the polar angle with an integer coefficient, then the intensity distribution has rotational symmetry, and the energy flow is radially symmetric and has the negative direction near the optical axis. In this second case, the intensity symmetry is not very pronounced, but with an odd dependence of the ratio of the semi-axes of the polarization ellipse, the focused field at each point has a local linear polarization, despite the rather complex form of the input field. In addition, we investigate the distribution of the longitudinal component of the Poynting vector. The obtained results may be used for the formation of focused light fields with the desired distributions of polarization, Poynting vector density, or spin angular momentum density in the field of laser manipulation and laser matter interaction.

We demonstrate that acousto-optic diffraction under certain conditions can be accompanied by inter-system photon–phonon entanglement. A photon diffracted during Stokes acousto-optic interaction of acoustic and optical vector beams represents a vector beam that manifests the intra-system entanglement between its states characterized by the different signs of circular polarization and orbital angular momentum. At the same time, a diffracted photon and an acoustic phonon emitted in the process of acousto-optic interaction demonstrate the inter-system entanglement between their circularly polarized vortex states.

An electric field propagating along a non-planar path can acquire geometric phases. Previously, geometric phases have been linked to spin redirection and independently to spatial mode transformation, resulting in the rotation of polarisation and intensity profiles, respectively. We investigate the non-planar propagation of scalar and vector light fields and demonstrate that polarisation and intensity profiles rotate by the same angle. The geometric phase acquired is proportional to j = ℓ + σ, where ℓ is the topological charge and σ is the helicity. Radial and azimuthally polarised beams with j = 0 are eigenmodes of the system and are not affected by the geometric path. The effects considered here are relevant for systems relying on photonic spin Hall effects, polarisation and vector microscopy, as well as topological optics in communication systems.

We propose vector modes based on inhomogeneously polarized Hermite–Gaussian (HG) vector beams, providing complete structural conservation of the beams during propagation. Like uniformly polarized mode beams, these beams provide structural stability (or invariance) of both the intensity and the polarization state, in turn ensuring the stability of other field characteristics, including the angular momentum. We determine the conditions imposed on the HG mode composition in the transverse components of the electromagnetic field in order to control the three-dimensional characteristics of the field, such as intensity, polarization, and spin angular momentum (SAM). For the visual analysis of the polarization state of inhomogeneously polarized beams, we use the transverse distribution of the vector of three Stokes parameters. The correspondence of the third Stokes parameter to the distribution of the longitudinal component of the SAM is used for experimental measurements. The theoretical analysis is clearly illustrated by numerical simulations and confirmed by experimental results.

Complex vector light fields have become a topic of late due to their exotic features, such as their non-homogeneous transverse polarisation distributions and the non-separable coupling between their spatial and polarisation degrees of freedom (DoF). In general, vector beams propagate in free space along straight lines, being the Airy-vector vortex beams the only known exception. Here, we introduce a new family of vector beams that exhibit novel properties that have not been observed before, such as their ability to freely accelerate along parabolic trajectories. In addition, their transverse polarisation distribution only contains polarisation states oriented at exactly the same angle but with different ellipticity. We anticipate that these novel vector beams might not only find applications in fields such as optical manipulation, microscopy or laser material processing but also extend to others.

Wavefront shaping of structured light beams is attracting considerable attention in optics and related technologies. Due to the potential benefits, it is crucial to develop versatile methods for controlling the wavefront in a compact space with the capacity for high‐throughput parallel processing. Herein, a unique concept is introduced for converting the wavefront of multiple structured light beams, which are periodically packed in a microscopic area. An experimental demonstration is provided by using transmissive planar optical elements consisting of a microarray of geometric phase based on nematic liquid crystals. The periodic microstructure is fabricated by the directed self‐organization of topological defects present in a nanoscale relief obtained by area‐selective surface modification. The conversion of multiple wavefronts is realized by using the Talbot self‐imaging effect of the microarray. The integrated geometric phase microarray has potential applications in vortex beam emitters to harness structured light, such as for optical manipulation and lithography.

Vector beams (VBs) and their superposition have found important applications in versatile fields such as optical communications, super-resolution microscopy and quantum information, and metasurfaces have enabled the miniaturization and integration of the optical systems manipulating the vector beams, providing potential applications to subwavelength regimes. In this work, we propose a metasurface to realize the superposition of profile-tunable tightly focused VBs, with the novel structured light fields generated. The metasurface is composed of two sets of orthogonal-nanoslit pairs arranged on the inner and outer rings. By realizing the chiral conversion of circularly polarized light with the slit-pairs which act as half-wave plates, and by creating helical phase profiles of optical vortices with the geometrical phase of rotational nano-slit pairs, two focused Bessel VBs are formed. By finely varying the diameters of two sets of rings, the doughnuts of the two Bessel VBs of different orders are tuned to be of the same size, and the superposition of the two VBs is realized. The theoretical analyses of the superimposed fields were presented, the FDTD simulations were performed to optimize the designed metasurfaces, and the experimental measurements were carried out to validate feasibility of the metasurface. The novel and interesting characteristics of the superposed fields different from those of the conventional VBs were demonstrated. This work will be of significance for classical and quantum applications of VBs in various fields.

With growing interest in the spatial dimension of light, multimode fibers, which support eigenmodes with unique spatial and polarization attributes, have experienced resurgent attention. Exploiting this spatial diversity often requires robust modes during propagation, which, in realistic fibers, experience perturbations such as bends and path redirections. By isolating the effects of different perturbations an optical fiber experiences, we study the fundamental characteristics that distinguish the propagation stability of different spatial modes. Fiber perturbations can be cast in terms of the angular momentum they impart on light. Hence, the angular momentum content of eigenmodes (including their polarization states) plays a crucial role in how different modes are affected by fiber perturbations. We show that, accounting for common fiber-deployment conditions, including the more subtle effect of light’s path memory arising from geometric Pancharatnam–Berry phases, circularly polarized orbital angular momentum modes are the most stable eigenbasis for light propagation in suitably designed fibers. Aided by this stability, we show a controllable, wavelength-agnostic means of tailoring light’s phase due to its geometric phase arising from path memory effects. We expect that these findings will help inform the optimal modal basis to use in the variety of applications that envisage using higher-order modes of optical fibers.

Use of metasurfaces to control the characteristics of electromagnetic waves is an emerging trend at present. Multifunctional metasurfaces, which can modulate multiple wave parameters, greatly reduce the complexity and enrich the functionality of optical systems. Herein, a high‐efficiency multifunctional metasurface for operation in the terahertz band is proposed and demonstrated. Use of a trilayer structure allows the working efficiency to reach 85% at the designed operating frequency. The phase and polarization states of the transmitted waves are modulated individually via subtle adjustment of the geometric parameters of each layer. Two terahertz‐band vector beam generators are demonstrated based on the proposed metasurface. The two devices individually generate radial and azimuthal terahertz vortex beams that can carry arbitrary orbital angular momentum. The experimental results demonstrate the validity of the proposed approach. This method represents a route toward easy fabrication of high‐performance phase and polarization modulation metasurfaces that can improve the information‐carrying capabilities of terahertz systems and offers benefits for structured light generation, optical information security, and optical communication applications.

We theoretically investigated the effect of a new type of twisting phase on the polarization dynamics and spin–orbital angular momentum conversion of tightly focused scalar and vector beams. It was found that the existence of twisting phases gives rise to the conversion between the linear and circular polarizations in both scalar and vector beams during focusing. The linear–circular polarization conversion further leads to an optical spin–orbital angular momentum transformation in the longitudinal component (LC). Therefore, even in a scalar optical field with a uniform linear polarization distribution, a circular polarization (spin angular momentum), and an orbital angular momentum (OAM) can appear in the cross-section and the longitudinal component, respectively, while being tightly focused. The novel distributions of the optical field, state of polarization (SOP) and OAM in the focal region are sensitively dependent on the twisted strength of the twisting phase. These results provide a more flexible manipulation of a structured optical field in the aspects of the optical field, SOP, and OAM.

Generally, the influence of initial phase of polarization distribution of incident vector beams always is ignored in its tight focusing, because it just induce the whole rotation of polarization distribution. In this paper, we show some distinctive effects induced by the initial azimuthal phase of polarization distribution in the tight focusing of radially polarized and azimuthal-variant hybrid vector beams. For these two types of vector beams, the initial azimuthal phase of polarization distribution induces two types rotation, the whole polarization rotation and the combined polarization rotation including the polarization distribution rotation and phase difference rotation, respectively. Furthermore, two methods are presented for modulating energy flow density and spin angular momentum density in the focal region, the synchronous and asynchronous rotation, which denote two polarization unit vectors with the same or different initial phase. Our results indicate the light–matter interaction can be induced by the polarization distribution rotation of incident vector beams in its tight focusing, and provide a possible connection with the rotational Doppler effect of optical vector beams.

A novel experimental setup for the generation of arbitrary vector beams is proposed. The system major includes two reflective liquid crystal spatial light modulators (RLC-SLM) and a polarizing beam splitting prism. Moreover, this method is not limited by the wavelength of light wave and the pixel size of SLM. Theoretical analysis shows that when Gaussian beam or a plane beam is illuminated on a computer-generated hologram (CGH) specially designed in this work, the complex amplitudes of the vector field’s two orthogonal polarization components may be changed by modifying the encoding parameters, resulting in a vector beam with arbitrary complex amplitude and polarization in the output field. The experimental results also show that the two independent coding channels of the device have good polarization-selective imaging ability, which greatly improves the flexibility of generating arbitrary vector beams.

The manipulation of the polarization states of the light transmitted through a scattering medium has become an emerging field due to the novel fundamental physics interest and potential applications. Here, the manipulation of the polarization states in the focusing high-resolution optical field (points and vector beams) after passing a scattering medium is theoretically and experimentally demonstrated. The vector transmission matrix (VTM) of a scattering medium is measured with the vector basis of orthogonally circular polarizations by the two-dimensional (2D) holographic grating combined with the four-step phase-shifting method. The incident wavefronts for the creation of desired high-resolution optical fields through a scattering medium are modulated according to the calculation with the VTM of the medium. The theoretical and experimental results show that the constructed high-resolution optical field with spatially variant states of polarization can be realized through frosted glass. These results provide a new way to vectorially manipulate the constructed high-resolution optical field by passing through a scattering medium.

Abstract Lasers are the pillars of modern photonics and sensing. Recent advances in microlasers have demonstrated its extraordinary lasing characteristics suitable for biosensing. However, most lasers utilized lasing spectrum as a detection signal, which can hardly detect or characterize nanoscale structural changes in microcavity. Here the concept of amplified structured light‐molecule interactions is introduced to monitor tiny bio‐structural changes in a microcavity. Biomimetic liquid crystal droplets with self‐assembled lipid monolayers are sandwiched in a Fabry–Pérot cavity, where subtle protein‐lipid membrane interactions trigger the topological transformation of output vector beams. By exploiting Amyloid β (Aβ)‐lipid membrane interactions as a proof‐of‐concept, it is demonstrated that vector laser beams can be viewed as a topology of complex laser modes and polarization states. The concept of topological‐encoded laser barcodes is therefore developed to reveal dynamic changes of laser modes and Aβ‐lipid interactions with different Aβ assembly structures. The findings demonstrate that the topology of vector beams represents significant features of intracavity nano‐structural dynamics resulted from structured light‐molecule interactions.

We report the design, fabrication and experimental validation of a THz all-dielectric multi-mode q-plate having a fixed rate of change of the optical axis. The device consists of space-variant birefringent slabs manufactured by 3D printing using melt-extruded Acrylonitrile Butadiene Styrene (ABS). The desired form birefringence is analytically evaluated and experimentally measured by the THz time domain spectroscopy technique. The manufactured q-plate design is characterized using a polarization-sensitive imaging setup. The full electric field spatial maps are acquired from the beam propagating through the q-plate. The device enables the realization of both radial and azimuthal vector beams at discrete frequency intervals by controlling the space-dependent orientation of the ordinary and extraordinary axes in the transverse plane with a multi-mode sequence.

We demonstrate the generation of a space-variant vector beam with catenary-shaped polarization states based on the polarization interferometry. With a spatial light modulator and a common path interferometric configuration, two orthogonally circularly polarized beams with different phase modulation overlap each other, yielding the vector beams. In addition, the polarization states of this vector beam are scalable to the arbitrary spatial distribution because of its great flexibility and universal applicability. It is expected that this vector beam may have many potential and intriguing applications in the micro/nano material processing, liquid crystal elements fabrication and optical micro-manipulation, and so on.

Terahertz (THz) vector beams with spatially textured polarization are proposed to steer the spin and spatial distributions of two interacting electrons in a quantum dot. We study theoretically the spatiotemporal evolution of the spin and the charge-current densities and quantify the behavior of entanglement by calculating the concurrence. Both aspects are shown to be controllable efficiently and on the picosecond (ps) time scale by the parameters of the driving fields. Analyzing two different materials, GaAs and InGaAs, with different electron g -factors, we study the relationship between the g -factor and type of spin–orbit coupling required to produce efficient interlevel transitions. The results are useful for applications of quantum dots as basic nanoscale hardware elements in quantum information technology and for producing swiftly the appropriate spin and charge currents on demand.

Nonradiating current configurations have been drawing the attention of the physics community for many years. It has been demonstrated recently that dielectric nanoparticles provide a unique platform to host such nonradiating modes, called “anapoles”. Here we study theoretically the excitation of such exotic anapole modes in silicon nanoparticles using structured light. Alternative illumination configurations, properly designed, are able to unlock hidden behavior of scatterers. Particularly, azimuthally polarized focused beams enable us to excite ideal anapole modes of magnetic type in dielectric nanoparticles. Firstly, we perform the decomposition of this type of excitation into its multipolar content and then we employ the T-matrix method to calculate the far-field scattering properties of nanoparticles illuminated by such beams. We propose several configuration schemes where magnetic anapole modes of simple or hybrid nature can be detected in silicon nanospheres, nanodisks and nanopillars.

In this work, we performed a Mueller matrix imaging analysis of two commercial optical components usually employed to generate and manipulate vector beams—a radial polarizer and a liquid-crystal q-plate. These two elements generate vector beams by different polarization mechanisms—polarizance and retardance, respectively. The quality of the vector beams relies on the quality of the device that generates them. Therefore, it is of interest to apply the well-established polarimetric imaging techniques to evaluate these optical components by identifying their spatial homogeneity in diattenuation, polarizance, depolarization, and retardance, as well as the spatial variation of the angles of polarizance and retardance vectors. For this purpose, we applied a customized imaging Mueller matrix polarimeter based on liquid-crystal retarders and a polarization camera. Experimental results were compared to the numerical simulations, considering the theoretical Mueller matrix. This kind of polarimetric characterization could be very helpful to the manufacturers and users of these devices.

We use a tunable commercial liquid-crystal device tuned to a quarter-wave retardance to study the generation and dynamics of different types of hybrid vector beams. The standard situation where the q-plate is illuminated by a Gaussian beam is compared with other cases where the input beam is a vortex or a pure vector beam. As a result, standard hybrid vector beams but also petal-like hybrid vector beams are generated. These beams are analyzed in the near field and compared with the far field distribution, where their hybrid nature is observed as a transformation of the intensity and polarization patterns. Analytical calculations and numerical results confirm the experiments. We include an approach that provides an intuitive physical explanation of the polarization patterns in terms of mode superpositions and their transformation upon propagation based on their different Gouy phase. The tunable q-plate device presents worthy advantages, since it allows a compact and efficient generation of pure and hybrid vector beams to study these effects.

The near-field characteristics of a radially-variant vector beam (RVVB) are analyzed by using the vectorial angular spectrum method. The non-paraxial RVVB can be decomposed into the propagating wave and the evanescent wave in near field. The coherent superposition of the longitudinal and transverse components of the RVVB results in a three-dimensional (3D) profile of the spin angular momentum flux density (SAM-FD). The evanescent wave part dominates the near field of a highly non-paraxial RVVB. The longitudinal component has a large impact on the 3D shape of the optical SAM-FD. Therefore, the 3D SAM-FD configuration of the RVVB can be manipulated by choosing the initial states of polarization arrangement. In particular, the transverse SAM-FD with a spin axis orthogonal to the propagation direction offers a promising range of applications spanning from nanophotonics and plasmonics to biophotonics.

Optical vortex beams, possessing spatial polarization or phase singularities, have intriguing properties such as the ability to yield super-resolved spots under focussing, and the ability to carry orbital angular momentum that can impart torque to objects. In this review, we discuss the means by which optical fibers, hitherto considered unsuitable for stably supporting optical vortices, may be used to generate and propagate such exotic beams. We discuss the multitude of applications in which a new class of fibers that stably supports vortices may be used, and review recent experiments and demonstration conducted with such fibers.

Two-dimensional metasurfaces are widely focused on for their ability for flexible light manipulation (phase, amplitude, polarization) over sub-wavelength propagation distances. Most of the metasurfaces can be divided into two categories by the material type of unit structure, i.e., plasmonic metasurfaces and dielectric metasurfaces. For plasmonic metasurfaces, they are made on the basis of metallic meta-atoms whose optical responses are driven by the plasmon resonances supported by metallic particles. For dielectric metasurfaces, the unit structure is constructed with high refractive index dielectric resonators, such as silicon, germanium or tellurium, which can support electric and magnetic dipole responses based on Mie resonances. The responses of plasmonic and dielectric metasurfaces are all relevant to the characteristics of unit structure, such as dimensions and materials. One can manipulate the electromagnetic field of light wave scattered by the metasurfaces through designing the dimension parameters of each unit structure in the metasurfaces. In this review article, we give a brief overview of our recent progress in plasmonic and dielectric metasurface-assisted nanophotonic devices and their design, fabrication and applications, including the metasurface-based broadband and the selective generation of orbital angular momentum (OAM) carrying vector beams, N-fold OAM multicasting using a V-shaped antenna array, a metasurface on conventional optical fiber facet for linearly-polarized mode (LP11) generation, graphene split-ring metasurface-assisted terahertz coherent perfect absorption, OAM beam generation using a nanophotonic dielectric metasurface array, as well as Bessel beam generation and OAM multicasting using a dielectric metasurface array. It is believed that metasurface-based nanophotonic devices are one of the devices with the most potential applied in various fields, such as beam steering, spatial light modulator, nanoscale-resolution imaging, sensing, quantum optics devices and even optical communication networks.