Light Field Manipulation Research Articles

Advanced Metasurface Imaging and Display Based on Multidimensional Light Field Manipulation (Invited)

Advanced Metasurface Imaging and Display Based on Multidimensional Light Field Manipulation (Invited)

Methods and Applications of Scattering Light Field Manipulation (Invited)

Methods and Applications of Scattering Light Field Manipulation (Invited)

Photonic Meta‐Neurons

AbstractArtificial intelligence (AI) has witnessed a growing integration into numerous domains of production and daily life. Such powerful AI has emerged from electronic simulations of human neurons. In the post‐Moore era, Von‐Neumann architecture and high energy consumption have posed challenges for the advancement of electronic AI. In light of these limitations, a new concept of photonic meta‐neurons is proposed, which holds the potential to address these issues by optically emulating biological neurons through the utilization of metasurfaces. Meta‐neurons could enable flexible modulation of photonic signals through hierarchical and high‐dimensional manipulation of light fields. The flat and thin design of the meta‐neuron reduces the spatial constraints. In comparison to electronic AI, meta‐neurons offer a range of desirable attributes, including the potential for achieving light‐speed processing, parallel computing, clean energy utilization, high energy efficiency, and an in‐memory computing architecture. The meta‐neuron concept can serve as a promising starting point for photonic AI. With its advantages of high‐speed computing and environmental friendliness, meta‐neurons will have broad applications in various fields, particularly for latency‐critical tasks.

Tunable full-space light field manipulation based on double-layer Ge2Sb2Te5 metasurfaces

Metasurfaces have the strong ability to reshape wave front and are attractive for a wide range of applications. However, metasurface based light field manipulation can be realized usually in either transmission or reflection space individually, which will limit its application scenario of metasuface. In this paper, we design a phase change material Ge2Sb2Te5 (GST) based double-layer dielectric metasurface in mid-infrared bands, which can achieve the light field manipulation in full space and dynamically control the focal intensity of reflected and transmitted light. As proof-of-concepts, two functional metasurfaces are designed and investigated: the first metasurface realizes the dynamically adjustable focus intensity in full-space under left circularly polarized (LCP) light incidence, the second metasurface is designed to provide spin-dependent bifocal in full space, which can generate custom designed two focal points under LCP or right circularly polarized (RCP) light incidence. Our proposed tunable full-space dielectric metasurfaces can be potentially applied for energy-harvesting, optical communication and optical imaging.

Generation of ultrafast tunable super-oscillation light fields

In this paper, we conceptually propose and numerically demonstrate the generation of ultrafast tunable super-oscillation (SO) light fields by tightly focusing a radially polarized Gaussian femtosecond pulse laser. It is shown that, as the fleeting time goes on within one-half cycle (0 fs < t < 200 fs), the light fields in the focal region can be converted from an Airy spot (>0.61λ/NA, where λ is the wavelength of incident beam and NA is the numerical aperture of objective lens), via a SO spot (<0.36λ/NA), to a super-resolved spot (<0.5λ/NA). We further uncover the rapid evolutions on the full width at half maximum, the normalized central intensity, and the side lobe of focused superoscillatory spots, thus supporting ultrafast adjustable SO light fields. In addition, the effect of primary spherical aberration on the focusing properties of SO spots is examined. The associated mechanism to yield such time-varying SO light fields is elucidated as well. The results presented here expand the flexibility of ultrafast light field manipulation and hold extensive applications in ultrafast and super-resolved imaging, high-density optical data storage, and high-efficiency particle trapping.

Multi-color complex spatial light modulation with a single digital micromirror device.

Spatial light modulators enabling complex light field manipulation has opened up many opportunities in biomedical imaging, holographic display, and adaptive optics. However, traditional spatial light modulators do not allow multi-color operations simultaneously due to their physical constraints, while multi-color modulations are highly desirable in many applications. To overcome this limitation, we demonstrate a multi-color spatial complex light field modulation with a single binary hologram on digital micromirror devices (DMD). This method combines several neighboring micro-mirror pixels into a giant single superpixel, in which the light field's amplitude and phase can be individually determined by internal pixel combinations, and the dynamic range of phase modulation can exceed 2π for the single wavelength. As a result, this extra phase modulation range offers an additional degree of freedom for independent multi-wavelength light modulation. Based on this scheme, multi-color light modulations have been demonstrated in a 2D plane as well as in multiple 3D holographic planes. Moreover, a dual-colored Airy beam has been realized using the same technique. These results bring complex light modulation into a multi-color regime, paving the way for practical applications in information display, imaging, and optical trapping.

Polarization-dependent reconfigurable light field manipulation by liquid-immersion metasurface.

Traditional grating lenses can accumulate phase for adjusting wavefronts, and plasmonic resonances can be excited in metasurfaces with discrete structures for optical field modulation. Diffractive and plasma optics have been developing in parallel, with easy processing, small size, and dynamic control advantages. Due to theoretical hybridization, structural design can combine advantages and show great potential value. Changing the shape and size of the flat metasurface can easily produce light field reflections, but changes in height are rarely cross-explored. We propose a graded metasurface with a single-structure periodic arrangement, which can mix the effects of plasmonic resonance and grating diffraction. As for solvents of different polarities, strong polarization-dependent beam reflections are produced, enabling versatile beam convergence and deflection. Dielectric/metal nanostructures with selective hydrophobic/hydrophilic properties can be arranged by the structural material specification to selectively settle the location of the solution in a liquid environment. Furthermore, the wetted metasurface is actively triggered to achieve spectral control and initiate polarization-dependent beam steering in the broadband visible light region. Actively reconfigurable polarization-dependent beam steering has potential applications in tunable optical displays, directional emission, beam manipulation and processing, and sensing technologies.

Generation of vector beams based on diffraction characteristics of a linear polarization hologram in coaxial recording.

Polarization holography is an effective tool for realizing light field manipulation and can be utilized to generate vector beams. Based on the diffraction characteristics of a linear polarization hologram in coaxial recording, an approach for generating arbitrary vector beams is proposed. Unlike the previous methods for generating vector beams, in this work, it is independent of faithful reconstruction effect and the arbitrary linear polarization waves can be used as reading waves. The desired generalized vector beam polarization patterns can be adjusted by changing the polarized direction angle of the reading wave. Therefore, it is more flexible than the previously reported methods in generating vector beams. The experimental results are consistent with the theoretical prediction.

Diffraction Characteristics of a Digital Micromirror Device for Computer Holography Based on an Accurate Three-Dimensional Phase Model

A digital micromirror device (DMD) has a wide range of applications in holographic display, light field manipulation, etc., due to its high-speed refresh rates. In order to precisely control the wavefront, the influence of the micromirror array structure of the DMD requires careful analysis. Based on an accurate three-dimensional phase model of DMD, we analyzed the diffraction characteristics of DMD. The model was established by accurately describing the phase distribution along each micromirror surface direction, and the distance between the point on the micromirror and the diffraction plane. The results showed that the orders of the DMD are the results of two groups of micromirrors interfering with each other, and a slight offset occurs when the incidence angle is twice the micromirror tilt angle, which can be removed by adjusting the incidence angle. The phase distribution results showed the main order of the DMD with all micromirrors in the on state can be approximated as a plane wave, which means that the hologram can be normally loaded on the DMD without worrying about phase disturbance from the micromirror array structure. This provides great convenience for computer holography based on DMD. Numerical simulations and experiments demonstrated the effectiveness of the work.

Optical image addition and subtraction based on electromagnetically induced transparency effect

The electromagnetically induced transparency (EIT) effect is a quantum coherence effect between different atomic transition channels. The absorption of the atomic ensemble is significantly reduced or even close to zero, and at the same time, this effect is accompanied by strong spectral dispersion near the resonant frequency of atoms, which is widely used in group velocity control, light pulse storage, and coherent manipulation on the light field. In the light pulse storage based on the EIT effect, the retrieval field is determined by the signal, coupling, and readout fields, enabling the retrieval field to be dynamically controlled by manipulating the spatial frequency components of the interacting light fields. In this paper, according to the EIT effect, we achieve experimentally the optical image addition and subtraction in the imaging plane of a 4&lt;inline-formula&gt;&lt;tex-math id="M2"&gt;\begin{document}$f$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20221560_M2.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20221560_M2.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; system through the coherent manipulation of the retrieval field via the interacting signal, coupling, and readout fields. Specifically, we first store the spatial frequency spectrum of a double-slit mask in the praseodymium-doped yttrium silicate crystal located in the confocal plane of the 4&lt;inline-formula&gt;&lt;tex-math id="M3"&gt;\begin{document}$f$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20221560_M3.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20221560_M3.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; system based on the EIT effect. Then, we utilize a specially designed mask containing the target objects and perform spatial filtering by using the spatial frequency spectrum of the double-slit mask through the retrieval of stored light pulse. By moving the double-slit mask, the addition and subtraction between the images of target objects can be achieved in the imaging plane of the 4&lt;inline-formula&gt;&lt;tex-math id="M4"&gt;\begin{document}$f$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20221560_M4.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20221560_M4.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; system. We present a theoretical model to describe the addition and subtraction between the target images through the EIT-based light pulse storage technique. The experimental results accord well with the theoretical prediction. Compared with the traditional scheme with a cosine grating filtering the spatial frequency spectrum, our method does not require the preparation of a spatial frequency filter, and only produces the first-order positive and negative diffraction images without the influence of the zeroth-order diffraction image. The optical image addition and subtraction based on the EIT effect provide a new approach to optical image processing. This approach is not limited to image addition or subtraction, and it can be extended to achieve more complex operations such as differentiation, enhancement, encryption, and decryption with rational design. Therefore, it can be widely used in areas such as coherent manipulation of light fields and dynamic optical image processing.

Multi-Dimensional Light Field Manipulation by Metasurfaces and Holographic Display Technology

Multi-Dimensional Light Field Manipulation by Metasurfaces and Holographic Display Technology

Structured Vector Field Manipulation of Terahertz Wave along the Propagation Direction Based on Dielectric Metasurfaces

AbstractThe generation and manipulation of vector light fields are of great significance for both fundamental research and industrial applications of polarized optics. In recent years, the spatial domain control of structured vector fields has gradually expanded from two‐ to three‐dimensional, including traditional optics and meta‐optics. Here, a new method to generate and manipulate structured vector light fields along the propagation direction is proposed, and the functionality in terahertz band using all‐silicon metasurfaces is demonstrated. The coherent superposition of orthogonal circularly polarized terahertz waves through long focal depth and multifocal metalens is completed, and varying phase differences between them in the propagation direction via path accumulation or initial phase design are introduced, thereby continuous variation or independently designed vector polarization distributions in multiple planes are obtained. It is worth mentioning that the proposed scheme is not only for the design of transverse electric field components, but also shows a strong ability for manipulation of the longitudinal component. This scheme realizes the polarization distribution designs of three‐dimensional vector fields in three‐dimensional space, and provides a new inspiration for the generation and manipulation of vector beams based on meta‐optics.

Dynamic bifunctional THz metasurface via dual-mode decoupling

Metasurfaces have powerful light field manipulation capabilities and have been researched and developed extensively in various fields. With an increasing demand for diverse functionalities, terahertz (THz) metasurfaces are also expanding their domain. In particular, integrating different functionalities into a single device is a compelling domain in metasurfaces. In this work, we demonstrate a functionally decoupled THz metasurface that can incorporate any two functions into one metasurface and switch dynamically through external excitation. This proposed metasurface is formed by the combination of split-ring resonators and phase change material vanadium dioxide ( VO 2 ). It operates in the single-ring resonant mode and double-ring resonant mode with varying VO 2 in insulating and metallic states, respectively. More importantly, the phase modulation is independent in two operating modes, and both cover a 360° cross-polarized phase with efficient polarization conversion. This characteristic makes it obtain arbitrary independent phase information on the metasurface with different modes to switch dual functions dynamically. Here, we experimentally demonstrate the functions of a tunable focal length and large-angle focus deflection of a THz off-axis parabolic mirror to verify the dual-function switching characteristics of the functionally decoupled metasurface. The functionally decoupled metasurface developed in this work broadens the way for the research and application of multifunctional modulation devices in the THz band.

Vector valley Hall edge solitons in superhoneycomb lattices

Topological edge solitons that bifurcate and inherit topological protection from linear edge states and, therefore, demonstrate immunity to disorder and defects upon propagation, attract considerable attention in a rapidly growing field of topological photonics. Valley Hall systems are especially interesting from the point of view of realization of topological edge solitons because they do not require external or artificial magnetic fields or longitudinal modulations of the underlying potential for the emergence of the topological phases. Here we report on the diverse types of vector valley Hall edge solitons forming at the domain walls between superhoneycomb lattices, including bright-dipole, bright-tripole, dark-bright, and dark-dipole solitons. In contrast to conventional scalar topological solitons, such vector states can be constructed as envelope solitons on the edge states from different branches and with different Bloch momenta. Such vector solitons can be remarkably robust, they show stable long-distance propagation and can bypass sharp bends of the domain wall. The existence of the counter-propagating valley Hall edge solitons at the same domain wall allows us to study their structural robustness upon collisions that can be nearly elastic. Our results illustrate richness of soliton families in the valley Hall systems and open new prospects for the light field manipulation and design of the nonlinear topological functional devices.

Nonlinear vectorial holography with quad-atom metasurfaces

Vectorial optical holography represents a solution to control the polarization and amplitude distribution of light in the Fourier space. While vectorial optical holography has been experimentally demonstrated in the linear optical regime, its nonlinear counterpart, which can provide extra degrees of freedom of light-field manipulation through the frequency conversion processes, remains unexplored. Here, we experimentally demonstrate the nonlinear vectorial holography through the second harmonic generation process on a quad-atom plasmonic metasurface. The quad-atom metasurface consists of gold meta-atoms with threefold rotational symmetry. Based on the concept of nonlinear geometric phase, we can simultaneously manipulate the phase and amplitude of the left and right circularly polarized second harmonic waves generated from the quad-atom metasurface. By superposing the two orthogonal polarization components, the quad-atom metasurface can produce nonlinear holographic images with vectorial polarization distributions. The proposed metasurface platform may have important applications in vectorial polarization nonlinear optical source, high-capacity optical information storage, and optical encryption.

Independent Light Field Manipulation in Diffraction Orders of Metasurface Holography

AbstractMetasurface holograms are novel optical elements with enormous potential because of the charming electromagnetic features, which can manipulate amplitude, phase, polarization state, and other parameters of light field via an elaborately designed subwavelength nanostructure array. Metagratings are extensively researched for controlling the feature of light in diffraction orders. However, a flexible and simple method is yearned for realizing independent wavefront manipulation in different orders. Here, a metasurface holography that can reconstruct various information in each diffraction order is demonstrated. The physical model is based on Jacobi–Anger expansion and iterative optimization, and both helicity‐dependent and birefringent metasurfaces can work compatibly with this proposed method to achieve arbitrary control of 1D and 2D orders. Specifically, information in 18 channels consisting of diffraction orders and polarization states is encoded in a single metasurface hologram. The approach provides promising and versatile optical elements for beam shaping, holographic display, optical storage, information encryption, etc.

Design of a four-energy-level vertical external surface-emission laser enabled on the waveguide grating structure

Membrane or film gain mediums have attracted great attention for their good thermal performances and light field manipulation properties, which are helpful for the power scaling of a laser. A membrane laser enabled on the waveguide grating structure is proposed and this design is flexible to manipulate optical properties by controlling the photonic density of states. Lasing behavior is theoretically analyzed based on the four-level rate equations. Results show that pump absorption is enhanced by about 35 times, which leads to improved laser efficiency. When the laser mode overlaps the resonant guided mode, the Purcell factor achieves 212, leading to enhanced emission rate, as well as an apparent decrease of relaxation oscillating amplitude and time delay. The present work offers a preliminary design and lasing behavior analysis of the vertical external surface-emission laser enabled on the waveguide grating structure.

Femtosecond laser plasmonic nano-printing metasurfaces for multiple-dimensional manipulation of light fields.

Metasurfaces enable the multidimensional manipulation of light fields in a subwavelength scale. However, the low-cost preparation of large-area metasurfaces is still a challenge. In this Letter, we first, to the best of our knowledge, use the laser plasmonic nano-printing technique to efficiently manufacture metasurfaces with multidimensional manipulation capability. By utilizing a phase-polarization mapping method, we fabricated a silicon-based metasurface for color display, and indium tin oxide-based metasurfaces for decoupled near- and far-field holographic displays. This flexible and efficient laser plasmonic nano-printing method has great potential in the preparation of large-area metasurfaces, and is of great significance to promote the practical application of metasurfaces.

Extraction of Inherent Polarization Modes from an m‐Order Vector Vortex Beam

Superposition of two independent orthogonally polarized beams is a conventional principle of creating a new light beam. Herein, it is intended to achieve the inverse process, namely, extracting inherent polarization modes from a single light beam. However, inherent polarization modes within a light beam are always intertwined so that a stable polarization is maintained during propagation in free space. To overcome this limitation, an approach that breaks the modulation symmetry of an m‐order vector vortex beam is reported, thereby unbinding the inherent polarization modes. Using polarization mode competition along with an optical pen, polarization modes within m‐order vector vortex beam are extracted at will in the focal region of an objective lens. This work treats the light beam as a treasure box, and polarization mode extraction is just like the key of the box. Whatever it is, one can just take it directly from the box. This physical thought conveys an entirely new principle of polarization modulation and paves the way for multidimensional manipulation of light fields.

Spatiotemporal manipulation of three-dimensional vectorlight fields

<p indent=0mm>Vector light fields show many exotic phenomena and applications that do not exist in scalar light fields, but current research of polarization optics mainly focuses on two-dimensional polarization manipulation. Recently, researchers have proposed a novel spatiotemporal manipulation method of synthetic vector light fields based on metasurfaces with asymmetric photonic spin-orbit interactions, which can in principle produce arbitrary three-dimensional vector light fields. This method expands polarization optics from two-dimensional space to three-dimensional space, provides some new ideas for the research of vector light field manipulation and its property in long-distance energy and information transmission, and has application prospects in the fields of focal field manipulation, light force control, laser communication, laser processing, etc.