Metasurface optical holography

Manipulating angular momentum of light relies on the change of geometric phase in anisotropic nanostructures or optical interface phenomena. Spin–orbit interactions demonstrated in normal incidence at a planar isotropic interface are conditioned by Brewster reflection, limited to the light beam with a single radial frequency in the k‐space. This study demonstrates a geometric (Pancharatnam–Berry) phase that overcomes Brewster angle limitations providing high variability in the modulation of light reflected from a planar isotropic interface. The examined geometric phase stems from the reflection anisotropy imitating the structural anisotropy of photoaligned liquid crystals and photonic metasurfaces. Using a geometric‐phase modulation of tightly focused light reflected from a glass slab, three modes of spin to orbital angular momentum conversion are demonstrated. The discovered reflective spin–orbit interaction allows for design of a double‐helix focusing sensor to be used in microscopy imaging for precise depth measurements (accuracy 109 nm and precision 7 nm in the range of 8 µm). Experiments with a focused astigmatic beam prove that a glass plate can perform very complex modulation of the geometric phase using illumination structuring. The results thus provide the foundation for the design of low‐cost geometric‐phase systems relying on the space‐variant reflection anisotropy.

Metasurface holography has emerged as a transformative technology with significant potential in information encryption, virtual displays, and high-capacity data storage. However, developing a holographic display system with ultrahigh information capacity and multidimensional multiplexing remains a major challenge. To address this issue, we propose a Janus metasurface holographic display scheme featuring asymmetric transmission and multi-depth imaging at microwave frequencies, enabled by complex-amplitude modulation. The modified three-dimensional holography method we proposed enables the complex-amplitude modulation devices to acquire the ability of manipulating multi-depth holographic displays. By simultaneously multiplexing the propagation direction and propagation distance of incident waves, a large number of distinct holographic images can be reconstructed throughout the entire propagation space. As a proof of concept, we experimentally demonstrate the reconstruction of five distinct letter images, each located on different planes along opposite propagation directions. The measured results show excellent agreement with simulations, validating the proposed strategy. This approach paves the way for metasurface-based holographic display systems featuring ultrahigh information capacity, robust holographic encryption, and high-efficiency data storage.

Metasurfaces, planar metamaterials consisting of a single layer or several layers of artificial structures, not only form the basis for fundamental physics research but also have considerable technological significance. Metasurfaces can locally modify the optical property within a subwavelength range, which can facilitate device miniaturization and system integration. Metasurfaces have shown extraordinary capabilities in the local manipulation of the light's amplitude, phase, and polarization, leading to a plethora of novel applications such as generalized Snell's law of refraction and photonic spin Hall effect. This progress report is focused on the recent advancements in the fundamental research of geometric metasurfaces and their applications in ultrathin optical devices, including planar metalenses, helicity multiplexed holograms, functionality switchable devices, polarization beam splitters, vector beam generation, arbitrary polarization control, and so on. The compactness, ease of fabrication, and unusual functionalities of these devices render geometric optical metasurface devices very attractive for new applications such as encryption, imaging, anti‐counterfeiting, optical communications, quantum science, and fundamental physics. This paper aims to bring readers some new insights, and to broaden the applications of geometric metasurfaces in more research fields of science and technology.

A waveguide holographic optical interconnect technique is used for signal distribution operations in a compact 3D waferpackaging configuration. This paper describes the design, fabrication and results of an integrated optical device which utilizesthis waveguide holographic optical interconnect technique. 1. INTRODUCTION The concept of using holograms to realize optical VLSI interconnection has been the subject of recent investigations[411. Inconventional holographic architectures, holographic optical elements (HOEs) that interconnect signals between the inputsources such as laser diodes (LDs) and the output receivers such as photodiodes cannot be closely packaged with the plane ofthe optoelectronic and microelectronic elements due to the F-number limitation of the HOEs. Holographic waveguide optical interconnections are, thus, introduced to solve this packaging problem [5,61• The resulting interconnect configuration combines integrated waveguide optics for beam guiding, waveguide grating couplers for beam coupling, and multiplexedwaveguide holograms for beam splitting in a monolithic form. As depicted in Figure 1 ,

We present a single-layer, transmissive metalens for focusing the orthogonal polarization components of incident light to two independent focal spots without affecting the initial orthogonal polarization states. To produce the required phase profile, the cross-shaped nanorod, as the unit cell of the metalens, is developed to support arbitrary combinations of two independent phase shifts (0- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\pi$ </tex-math></inline-formula> ) of transverse electric and transverse magnetic polarized light. A deep neural network is trained to generate the design parameters of each unit cell efficiently and accurately. The metalens is simulated with finite-difference time-domain method and good agreements are observed comparing with theoretical prediction. This work provides a new solution to multi-foci metalens and polarization beam splitter and may find potential applications in deep sensing, holography, information encryption and display.

Noise is usually undesired yet inevitable in science and engineering. However, by introducing the engineered noise to the precise solution of Jones matrix elements, we break the fundamental limit of polarization multiplexing capacity of metasurfaces that roots from the dimension constraints of the Jones matrix. We experimentally demonstrate up to 11 independent holographic images using a single metasurface illuminated by visible light with different polarizations. To the best of our knowledge, it is the highest capacity reported for polarization multiplexing. Combining the position multiplexing scheme, the metasurface can generate 36 distinct images, forming a holographic keyboard pattern. This discovery implies a new paradigm for high-capacity optical display, information encryption, and data storage.

Information encryption and security is a prerequisite for information technology, which can be realized by an optical metasurface owing to its arbitrary manipulation over the wavelength, polarization, phase, and amplitude of light. So far information encoding can be implemented by the metasurface in one-dimensional (1D) mode (either wavelength or polarization) only with several combinations of independent channels. Herein, we design dielectric metasurfaces by multiplexing for information encoding in a two-dimensional (2D) mode of both wavelength and polarization. Sixty-three combinations made out of six independent channels by two circular polarization states (RCP and LCP) and three visible wavelengths (633, 532, and 473 nm) are experimentally demonstrated, in sharp contrast with seven combinations by three independent channels in 1D mode. This 2D mode encoding strategy enhances the encryption security dramatically and paves a novel pathway for escalating the security level of information in multichannel ...

Metasurfaces (MSs) are being extensively researched owing to their ability to modulate the polarization and wavefront of electromagnetic (EM) waves in a flexible manner, which usually offer significant advantages including ultra-thinness, low losses, and easy fabrication. However, conventional MSs typically operate well only with a single polarization. Here, we propose a novel design strategy for a terahertz (THz) reflective-mode MS that relies on a single unit-cell arrangement combining propagation phase and geometric phase. Our designed MS can achieve multiple wavefront manipulations in reflection mode, not limited to circular polarization (CP) transformation, but also enabling linear polarization (LP) conversion. The MS we propose consists of a periodic array of bilayered metal patterned resonator structures sandwiched by a dielectric substrate. The metallic resonator is made of the outer single-split-ring (SSR) and C-shaped slot (CSS), inner double-split-ring (DSR), and its complementary structure. With this design, the MS is capable of converting a LP wave to its orthogonal counterpart at lower frequency (f1=0.7THz) after reflection. Additionally, at higher frequency (f2=1.4THz), the proposed MS can also convert the right-handed CP (RCP) to left-handed CP (LCP) upon reflection or vice versa. The 2π phase full coverage of the orthogonal LP and CP waves can be achieved independently and simultaneously by adjusting the opening and orientation angles of the SSR based on propagation phase, and orientation angle of the DSR based on geometric phase. We numerically demonstrate beam deflection, planar focusing, and the vortex beam for both reflected orthogonal LP and CP waves with three representative MSs to provide proof of concept. These findings reveal the great potential for multifunctional devices for dual-polarization in imaging and communication systems.

We have demonstrated an approach of relatively rapid fabrication of two-dimensional (2-D) photonic crystals (PCs) with embedded defects by combining a custom-built blue-laser-writer and the technique of optical holography. The blue-laser-writer is used to define various defect patterns first, and then the optical holography is used to create 2-D PCs on the samples with the predefined defects. A beam splitter was fabricated based on this new method and characterized.

Optical metasurfaces, consisting of spatially variant meta-atoms, represent a new kind of optical platform for controlling the wavefront of light, with which many interesting applications, such as metalens and optical holography, have been successfully demonstrated. Further extension of the optical functionalities of metasurfaces into the nonlinear optical regime has led to unprecedented control over the local optical nonlinear generation processes. It has been shown that the nonlinear optical metasurface with achiral geometries could exhibit intrinsic optical activity in second- and third- harmonic generations. In this work, we propose an alternative approach for achieving strong nonlinear optical activity in achiral plasmonic metasurfaces by exploiting the lattice surface modes of plasmonic metasurfaces. Specifically, we theoretically and experimentally demonstrate the strong circular dichroism for second harmonic generation (SHG) on plasmonic metasurfaces consisting of split-ring resonator meta-atoms. The strong nonlinear circular dichroism is attributed to the contribution from lattice surface modes at fundamental wavelengths. Our findings may open new routes to design novel nonlinear optical devices with strong optical activity.

See-through head-up 3D display is being reported, which uses a commercial projector as the light source and a lens array in the form of holographic optical element (HOE). By introducing novel technique in the fabrication process of the HOE based lens array, we have significantly simplified the display system by not using any collimation optics. Light field reconstructions of a 3D scene of size 20cm (Width) × 10cm (Height) × 5 cm (Depth) is successfully demonstrated with a view angle of 10-degrees.

The Optica Digital Holography and Three-Dimensional Imaging Topical Meeting (DH) 2024 in Paestum, Italy, brought together a vibrant hub for global experts to showcase cutting-edge research and industry pioneers to discuss the latest developments in digital holography (DH) and 3D imaging techniques. This meeting's impact is further amplified by a dedicated feature issue across three prestigious Optica journals: Applied Optics, Journal of the Optical Society of America A, and Biomedical Optics Express. This introduction summarizes the diverse and high-quality contributions, highlighting key advancements and applications that are shaping the future of DH and imaging.

We report a strategy for multitasking in a shared aperture by involving split ring resonators (SRRs) and cross bar operated at low and upper frequencies in an emerging chessboard-configured meta-atom. By individually rotating the SRRs with endowing geometric phase, two similar functions with flipped phases are realized at low band under two circularly polarized waves, whereas by involving both orientation and structural variations of cross bars (geometric and propagation phase), two independent optical functions can be engineered at high frequency. To verify the significance of our approach, a proof-of-prototype sample is demonstrated for wavefront manipulation by producing an anomalous reflection, focusing, and vortex beam. Our finding in frequency-and-spin multiplexing is expected to trigger great interest in high electromagnetic/optical integration with boosted information capacity and a new degree of freedom.

Metalenses have the potential to revolutionize optical devices into the next generation of consumer devices. Through new inventive strategies, metalenses with advanced functionalities have been released to integrate multiple responses into a single flat device. Here, we design metalenses that are sensitive to the incident spin angular momentum to provide three distinct modes based on the handedness of the incident and transmitted light. Propagation phase is employed to encode a hyperbolic lens phase to the metalens, while geometric phase is exploited for additional spin-selective properties. We experimentally demonstrate two different metalenses: the co-polarized channels function as a standard metalens, while the cross-polarized channels (1) deflect and (2) introduce orbital angular momentum to the transmitted light. We experimentally characterize the metalenses and prove their use for spin-selective imaging of visible light. We envision that such trichannel metalenses could be employed in chiral bioimaging, optical computing, and computer vision.

Achieving kaleidoscopic wavefront controls or versatile distinct multifunctions with a thin flat plate are pivotal yet challenging in integrated optics. Anisotropic metasurface affords us an efficient recipe primarily for arbitrary linear polarization, but is ceased to be efficient for multiple functionalities at arbitrary spin states. Here, we report a strategy for multitasking in a shared aperture by involving split ring resonators (SRRs) and cross bar operated at low and upper frequencies in an emerging chessboard-configured meta-atom. By individually rotating the SRRs with endowing geometric phase, two similar functions with flipped phases are realized at low band under two circularly polarized waves, whereas by involving both orientation and structural variations of cross bars (geometric and propagation phase), two independent optical functions can be engineered at high frequency. The key for such multitasking benefits from the totally suppressed interference between both structures and the completely spin-decoupled dual-phases at high frequency. To verify the significance of our approach, a proof-of-prototype sample is demonstrated for wavefront manipulation by integrating quad vortices and two-dimensional holograms, etc. Our finding in frequency-and-spin multiplexing is expected to trigger great interest in high electromagnetic/optical integration with boosted information capacity and a new degree of freedom.