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Metasurface holography: from fundamentals to applications
Lingling Huang, Shuang Zhang, Thomas Zentgraf
TL;DR
Conventional holograms face pixel-size and space-bandwidth limitations that constrain high-performance applications. This review synthesizes metasurface holography’s mechanisms, wavefront-control strategies, multiplexing approaches, and active-device developments, highlighting its high-resolution imaging and expanded information capacity.
Problem
Conventional holograms have larger pixels and more limited space-bandwidth products than metasurface holograms, restricting holographic performance.
Method
The review classifies metasurfaces and synthesizes strategies for controlling free-space and surface waves, multiplexing holographic channels, and enabling active displays.
Results
Metasurface holography provides high-resolution, low-noise, high-precision reconstruction, large space-bandwidth products, multiplexed channels, and active holographic-display approaches.
Takeaways & Limitations
Metasurface holography supports optical control of free-space and surface-plasmon-polariton wavefronts and serves as a platform for large-capacity holographic displays and data storage.
Takeaways & Limitations
Simultaneously achieving real-time reconfigurability, high efficiency, and large field of view for scattered light remains unresolved.
Abstract
from arXiv · showhide
Holography has emerged as a vital approach to fully engineer the wavefronts of light since its invention dating back to the last century. However, the typically large pixel size, small field of view and limited space-bandwidth impose limitations in the on-demand high-performance applications, especially for three-dimensional displays and large-capacity data storage. Meanwhile, metasurfaces have shown great potential in controlling the propagation of light through the well-tailored scattering behavior of the constituent ultrathin planar elements with a high spatial resolution, making them suitable for holographic beam-shaping elements. Here, we review recent developments in the field of metasurface holography, from the classification of metasurfaces to the design strategies for both free-space and surface waves. By employing the concepts of holographic multiplexing, multiple information channels, such as wavelength, polarization state, spatial position and nonlinear frequency conversion, can be employed using metasurfaces. Meanwhile, the switchable metasurface holography by the integration of functional materials stimulates a gradual transition from passive to active elements. Importantly, the holography principle has become a universal and simple approach to solving inverse engineering problems for electromagnetic waves, thus allowing various related techniques to be achieved.
1 Introduction to metasurface holography
Metasurface holography combines holographic wavefront recording with nanoscale resonators whose positions and scattering properties are precisely patterned. This approach enables high-resolution holograms and supports control of free-space and surface waves, multiplexed information channels, and active functionality.
- 1 Introduction to metasurface holography: Metasurface holograms map holographic configurations onto nanoscale resonators patterned at an interface.The resonators’ positions and local scattering properties are precisely controlled.
- 1 Introduction to metasurface holography: Compared with conventional holograms, metasurfaces offer unprecedented spatial resolution, low noise, and high-precision reconstructed images.Ultrathin holograms can record both phase and amplitude information of the wavefront.
- 1 Introduction to metasurface holography: The review covers holographic concepts, processing procedures, metasurface mechanisms and classifications, and control of free-space and surface plasmon polariton waves.It presents both foundational principles and recent advancements in metasurface holography.
- 1 Introduction to metasurface holography: Holographic multiplexing enables multiple information channels using position, polarization, angle, wavelength, and nonlinear frequency conversion.The supplied overview identifies multiplexing as a route to multiple recording and display channels.
- 1 Introduction to metasurface holography: Functional materials enable active metasurface holograms, extending metasurface holography beyond passive elements.Examples include graphene oxide and GST-integrated holograms, alongside 2D and phase-change materials.
2 Principle of metasurface holography
Metasurface holography classifies recording media by their materials and operating mechanisms, then designs holograms by computing and encoding complex optical information. Different metasurface principles provide phase, amplitude, polarization, and efficiency control, while introducing mechanism-dependent limitations.
- Metasurface classification: Metasurfaces are classified as plasmonic, all-dielectric, geometric, or Huygens structures according to constituent materials and operating mechanisms.Plasmonic structures use localized plasmon resonances; dielectric structures use high-index particles; geometric structures use Pancharatnam–Berry phase; Huygens structures use electric and magnetic responses.
- Hologram design procedure: Hologram design formulates object and hologram models, numerically synthesizes a complex computer-generated hologram, and encodes its amplitude and/or phase on the recording medium.Objects may be represented by elementary diffracting elements or analytical models under monochromatic illumination, while different kernels yield Fresnel or Fourier holograms.
- Geometric metasurface holography: Geometric metasurfaces provide spatially oriented phase control and enable three-dimensional reconstruction through polarization-converted scattered light.For circularly polarized incidence, the desired local phase shifts appear in the opposite-handedness polarization state.
- Geometric metasurface holography: 80% efficiency was demonstrated for a reflection-type PB-phase metasurface hologram by combining accurate phase control with a ground-metal reflect-array.The design avoided a complicated fabrication process, and reconstruction distance is inversely proportional to incident wavelength under the paraxial approximation.
- All-dielectric holography: All-dielectric geometric metasurfaces can support high-efficiency transmission holography by using form birefringence for circular-polarization conversion and orientation-dependent phase modulation.Silicon nanopost arrays with spatially varying orientations were used for multicolor holographic images.
- Plasmonic holography: Plasmonic resonance-tuning metasurfaces offer limited spectral bandwidth and introduce additional phase noise into holographic images.Their Babinet-based complementary design requires an extra lookup table for local phase and amplitude control and blocks the co-polarized direct-transmission component for linearly polarized incidence.
3 Holographic multiplexing
Metasurface holographic multiplexing expands space-bandwidth and information capacity through color, polarization, and algorithmic channels. These approaches support low-cost, high-performance, large-capacity holographic displays and data storage while addressing efficiency, crosstalk, and fabrication challenges.
- 3 Holographic multiplexing: Multiplexing metasurface holograms targets enormous space-bandwidth product and information capacity, potentially enabling low-cost, high-performance, large-capacity displays and data storage.Metasurfaces may circumvent limitations of traditional photorefractive-crystal techniques, including photobleaching.
- Color holography: Color holography independently manipulates multiple wavelength channels using spatially multiplexed subpixels, dielectric nanoblocks, or broadband geometric-phase nanoslits.Three kinds of silicon nanoblocks can simultaneously manipulate the three primary colors, while broadband PB-phase designs support separate RGB computer-generated holograms.
- Color holography: Multicolor operation remains limited by efficiency and crosstalk: narrow resonances reduce crosstalk but require multiple components and degrade viewing angles, whereas broadband designs demand delicate off-axis tuning.Recent demonstrations of chromatic-aberration correction may aid compact metasurface color holographic devices.
- Polarization multiplexing: Polarization multiplexing uses birefringent metasurfaces to encode distinct holographic patterns on orthogonal polarization states with little far-field interference or crosstalk.Tailored dielectric resonators can superpose two independent arbitrary phase profiles on orthogonal linear, circular, or elliptical polarization states.
- Hybrid multiplexing algorithms: Synthetic-spectrum holographic algorithms formulate multiplexing as combinatorial optimization across display channels and can produce phase-only holograms reconstructing different objects in different Fresnel-range planes.Appropriate feedback operations increase convergence speed and significantly enlarge the multiplexing capacity Pmax.
4 Surface wave holography
Surface-wave holography engineers confined SPP wavefronts through metasurface coupling and phase matching, enabling multiplexed, spin-selective, tunable, and orbital-angular-momentum-selective control. Its realization requires addressing momentum matching, vectorial excitation, near-field interference, and finite propagation distance.
- 4 Surface wave holography: Surface holography controls surface-wave wavefronts, including subwavelength-confined SPPs, by reconfiguring or coupling them from far-field excitation.SPPs provide nanoscale light confinement, but surface holography fundamentally differs from free-space holography because the reconstructed wavefronts are surface waves.
- 4 Surface wave holography: Plasmonic holograms reconstruct SPP or radiative fields using interference recording, equal-phase grooves, and metasurface coupling schemes.The reviewed approaches include SPP color holography, etched phase grooves, and coupling SPPs to far-field radiation.
- 4 Surface wave holography: Geometric-phase nanoapertures enable independent spin-selective SPP control, while slit-pair resonators set phase through θ1 + θ2 and amplitude through sin(θ1 − θ2).The phase sign depends on incident spin, and the resonator amplitude is proportional to sin(θ1 − θ2).
- 4 Surface wave holography: Interference between target SPP profiles can be tuned from constructive to destructive, producing intensity-tunable closed-loop SPP profiles that trap or release nanoparticles.Changing the target profiles’ initial phase gradually tunes the interference and enables SPP-force manipulation of nanoparticle motion.
- 4 Surface wave holography: Surface holography must address momentum matching, vectorial SPP excitation, near-field interference among wavefronts or diffraction orders, and finite propagation distance.Coupling free-space waves to SPPs requires matching their wave vectors; amplitude and phase conditions must reflect the SPPs’ vectorial nature.
- 4 Surface wave holography: Holographic SPP couplers can selectively detect the orbital angular momentum of free-space vortex beams by shaping the spatial form of the SPP beam.The metasurface hologram uses interference between a free-space vortex object beam and a reference plasmonic beam.
5 Nonlinear holography
Nonlinear metasurface holography extends phase tailoring to frequency conversion, enabling coherent generation and manipulation of new frequencies with controlled polarization and wavefronts. These capabilities support multiplexed holographic images and applications including security, data storage, and optical encryption.
- Nonlinear phase control: Nonlinear metasurfaces continuously control the phase of local nonlinear polarizability during harmonic generation, depending on the emitted and fundamental-wave spins.The nonlinear polarizability follows distinct phase factors for harmonic generation with the same or opposite spin relative to the fundamental wave.
- Nonlinear holographic multiplexing: Combining nonlinear metasurfaces with holography optimization enables one metasurface to convert a fundamental wave into multiple beam profiles or images.Split-ring resonators provide strong polarization properties and high second-harmonic generation efficiency, supporting nonlinear holographic multiplexing.
- Polarization-selective holography: A double-layer V-antenna metasurface reconstructed Aleph and Shin from separate layers selected by vertical and horizontal input polarizations, respectively.Each image was recreated only by the properly polarized input beam and emanated from a single nanoantenna layer.
- Nonlinear phase control: Every combination of incident and outgoing polarizations can acquire a susceptibility-dependent phase factor, enabling full control over the 0–2π phase range.This framework expands nonlinear metasurfaces toward higher-order nonlinear holography by combining linear and nonlinear polarization terms.
- Applications: Symmetry-controlled high-harmonic generation enables efficient engineering of both polarization and wavefronts for anti-counterfeiting, security identification, multidimensional data storage, and optical encryption.These applications rely on the ability to encode information through nonlinear optical processes and high-order harmonic generation.
6 Active metasurface holography
Active metasurface holography transitions passive holograms toward dynamically tunable, adaptive, and rewritable elements by integrating functional materials, active components, or mechanically deformable substrates. These approaches enable reconfigurable holographic images and versatile electromagnetic-wave control through modulation of optical properties, scattering, phase, and amplitude.
- 6 Active metasurface holography: Functional materials such as phase-change and two-dimensional materials enable active metasurface holograms with tunable local optical properties.Examples include GST, VO2, graphene, and borophene, modulated through thermal excitation, voltage bias, magnetic fields, optical pumping, or mechanical deformation.
- 6 Active metasurface holography: Femtosecond-laser photoreduction of graphene oxide in photopolymers controls the refractive index of reduced graphene oxide for rewritable three-dimensional holography.The figure identifies wide viewing angles as a capability of graphene-oxide active holograms.
- 6 Active metasurface holography: Inserting GST into a dielectric medium shifts the resonance condition and produces a large reflection-coefficient phase shift.GST can be switched between crystallized and amorphous states.
- 6 Active metasurface holography: Stretching a metasurface hologram by factor s enlarges the hologram image and moves its image plane away from the unstretched position by s^2 − 1.This mechanically induced image-plane shift enables reconfigurable holograms observed at a fixed position.
- 6 Active metasurface holography: Varactors and diodes enable dynamic microwave electromagnetic-wave control, including programmable 1-bit coding metasurface holograms that generate arbitrary holographic images.The scattering state of each unit cell is controlled through input programming voltages.
- 6 Active metasurface holography: Active metasurface holography supports simultaneous phase and amplitude modulation, enabling versatile devices with adaptive and rewritable functionalities.These functionalities are summarized in the paper’s Table 2.
7 Holographic-related techniques and perspectives
Metasurface holography uses holographic strategies to inverse-engineer desirable free-space or surface-wave fields, while remaining challenges concern modeling, design, materials, and real-time reconfigurability. Its broad control over optical parameters also supports applications in information processing, metrology, sensing, and security.
- Inverse engineering and modeling: Holographic strategies provide a flexible tool for inverse engineering of free-space beams and surface waves with desirable field distributions.Existing point-source, polygonal-mesh, GS, and genetic algorithms can be applied directly to metasurfaces.
- Materials and design: Metasurface development seeks low-loss, durable, CMOS-compatible materials and scattering elements that jointly control local amplitude, phase, and polarization.Demonstrated material systems support all-optical, non-volatile, switchable, and high-resolution holography.
- Active and reconfigurable holography: Simultaneous real-time reconfigurability, high efficiency, and large field of view remains unachieved in active metasurface holography.Candidate reconfiguration approaches include thermal-effect phased arrays, electro-optical modulation, liquid crystals, programmable gate arrays, and switchable diodes.
- Optical information processing: Metasurface-based computer-generated holograms support spatial filtering, beam shaping, deflection, beam splitting, optical interconnects, communications, computing, and information display.These uses illustrate the universality and simplicity of holographic strategies for practical optical techniques.
- Metrology, sensing, and security: Metasurface holograms enable optical metrology, sensing, and security applications through displacement measurement, optical-path monitoring, molecular responses, and encrypted patterns.Security can exploit control over polarization, wavelength, position, and material properties.
8 Summary
The overview traces metasurface holography from early holographic image generation to advanced holographic multiplexing, covering free-space and surface-plasmon-polariton wavefront control. It also highlights metasurface holography’s potential for arbitrary beam control, new phenomena, and nanotechnology applications.
- Summary: The review traces metasurface holography from early holographic image generation to advanced holographic multiplexing.It presents the field’s history and development across these stages.
- Summary: The article presents metasurface-holography approaches for controlling free-space and surface plasmon polariton wavefronts.Its discussion is limited to electromagnetic metasurfaces, while acoustic holography is noted as a separate application area.
- Summary: Holography-related metasurfaces may reveal unanticipated phenomena and applications while advancing arbitrary beam control and nanotechnology products.The authors characterize these developments as important for realizing arbitrary beam control and stimulating new product development.