Ultraviolet-Visible Multifunctional Vortex Metaplates by Breaking Conventional Rotational Symmetry

Spatial Control of 2D Nanomaterial Electronic Properties Using Chiral Light Beams

Single-layer two-dimensional (2D) nanomaterials exhibit physical and chemical properties which can be dynamically modulated through out-of-plane deformations. Existing methods rely on intricate micromechanical manipulations (e.g., poking, bending, rumpling), hindering their widespread technological implementation. We address this challenge by proposing an all-optical approach that decouples strain engineering from micromechanical complexities. This method leverages the forces generated by chiral light beams carrying orbital angular momentum (OAM). The inherent sense of twist of these beams enables the exertion of controlled torques on 2D monolayer materials, inducing tailored strain. This approach offers a contactless and dynamically tunable alternative to existing methods. As a proof-of-concept, we demonstrate control over the conductivity of graphene transistors using chiral light beams, showcasing the potential of this approach for manipulating properties in future electronic devices. This optical control mechanism holds promise in enabling the reconfiguration of devices through optically patterned strain. It also allows broader utilization of strain engineering in 2D nanomaterials for advanced functionalities in next-generation optoelectronic devices and sensors.

Functionality Expansion of Guided Mode Radiation via On-Chip Metasurfaces

On-chip metasurfaces play a crucial role in bridging the guided mode and free-space light, enabling full control over the wavefront of scattered free-space light in an optimally compact manner. Recently, researchers have introduced various methods and on-chip metasurfaces to engineer the radiation of guided modes, but the total functions that a single metasurface can achieve are still relatively limited. In this work, we propose a novel on-chip metasurface design that can multiplex up to four distinct functions. We can efficiently control the polarization state, phase, angular momentum, and beam profile of the radiated waves by tailoring the geometry of V-shaped nanoantennas integrated on a slab waveguide. We demonstrate several innovative on-chip metasurfaces for switchable focusing/defocusing and for multifunctional generators of orbital angular momentum beams. Our on-chip metasurface design is expected to advance modern integrated photonics, offering applications in optical data storage, optical interconnection, augmented reality, and virtual reality.

Fluid-responsive tunable metasurfaces for high-fidelity optical wireless communication

Optical wireless communication (OWC), with its blazing data transfer speed and unparalleled security, is a futuristic technology for wireless connectivity. Despite the significant advancements in OWC, the realization of tunable devices for on-demand and versatile connectivity still needs to be explored. This presents a considerable limitation in utilizing adaptive technologies to improve signal directivity and optimize data transfer. This study proposes a unique platform that utilizes tunable, fluid-responsive multifunctional metasurfaces offering dynamic and unprecedented control over electromagnetic wave manipulation to enhance the performance of OWC networks. We have achieved real-time, on-demand beam steering with vary-focusing capability by integrating the fabricated metasurfaces with different isotropic fluids. Furthermore, the designed metasurfaces are capable of polarization-based switching of the diffracted light beams to enhance overall productivity. Our research has showcased the potential of fluid-responsive tunable metasurfaces in revolutionizing OWC networks by significantly improving transmission reliability and signal quality through real-time adjustments. The proposed methodology is verified by designing and fabricating an all-dielectric metasurface measuring 500 μm × 500 μm and experimentally investigating its fluid-responsive vary-focal capability. By incorporating fluid-responsive properties into spin-decoupled metasurfaces, we aim to develop advanced high-tech optical devices and systems to simplify beam-steering and improve performance, adaptability, and functionality, making the devices suitable for various practical applications.

Full-Dimensional Geometric-Phase Spatial Light Metamodulation

Full-dimensional spatial light modulation requires simultaneous, arbitrary, and independent manipulation of the spatial phase, amplitude, and polarization. This is crucial for leveraging the complete physical dimension resources of light. However, full-dimensional metamodulation can be challenging due to the need for multiple independent control factors. To address this challenge, here we propose parallel-tasking metasurfaces to enable full-dimensional spatial light metamodulation based fully on the geometric-phase concept. Indeed, the meta-atoms are divided into several subphases, each of which serves as an independent control factor to manipulate light phase, amplitude, and polarization through geometric phase, interference, and orthogonal polarization superposition, respectively. Therefore, the macroscopic group of meta-atoms leads to metasurfaces that can achieve broadband full-dimensional spatial light metamodulation, as demonstrated by various types of structured light generation. This approach paves the way to future wide applications of light manipulation enabled by full-dimensional spatial light metamodulation.

Multi-focus composite spiral zone plate to generate focused vortices with the comparable intensity based on genetic algorithm

In this study, we introduce an optical element, named Multi-focus Composite Spiral Zone Plate (MFCSZP), to generate multi focused vortices with approximately equal intensity along the optical axis. The genetic algorithm (GA) is used to optimize the parameters of the MFCSZP, which avoids manual parameter adjustment and improves computational efficiency. We analyze the focusing properties of the constructed MFCSZP theoretically and experimentally. The results provide evidence for its capability to generate multiple focused vortices with comparable peak intensities verified through experiment. This work shows the powerful ability of intelligent algorithms in the optimization of complex optical elements. The proposed optical element showcases potential applications within research areas of optical trapping and laser machining.

Spin-isolated ultraviolet-visible dynamic meta-holographic displays with liquid crystal modulators

Wearable displays or head-mounted displays (HMDs) have the ability to create a virtual image in the field of view of one or both eyes. Such displays constitute the main platform for numerous virtual reality (VR)- and augmented reality (AR)-based applications. Meta-holographic displays integrated with AR technology have potential applications in the advertising, media, and healthcare sectors. In the previous decade, dielectric metasurfaces emerged as a suitable choice for designing compact devices for highly efficient displays. However, the small conversion efficiency, narrow bandwidth, and costly fabrication procedures limit the device's functionalities. Here, we proposed a spin-isolated dielectric multi-functional metasurface operating at broadband optical wavelengths with high transmission efficiency in the ultraviolet (UV) and visible (Vis) regimes. The proposed metasurface comprised silicon nitride (Si₃N₄)-based meta-atoms with high bandgap, i.e., ∼ 5.9 eV, and encoded two holographic phase profiles. Previously, the multiple pieces of holographic information incorporated in the metasurfaces using interleaved and layer stacking techniques resulted in noisy and low-efficiency outputs. A single planar metasurface integrated with a liquid crystal was demonstrated numerically and experimentally in the current work to validate the spin-isolated dynamic UV-Vis holographic information at broadband wavelengths. In our opinion, the proposed metasurface can have promising applications in healthcare, optical security encryption, anti-counterfeiting, and UV-Vis nanophotonics.

Metasurface-Enabled On-Chip Manipulation of Higher-Order Poincaré Sphere Beams

An integrated way to generate and manipulate higher-order Poincaré sphere beams (HOPBs) is a sought-after goal in photonic integrated circuits for high-capacity communication systems. Here, we demonstrate a novel method for on-chip generation and manipulation of HOPBs through combining metasurface with optical waveguides on lithium niobate on insulator platform. With phase modulation by a diatomic geometric metasurface, guided waves are extracted into free space with a high signal-to-noise ratio in the form of two orthogonal circularly polarized optical vortices which are linearly superposed into HOPBs. Meanwhile, a dual-port waveguide crossing is established to reconfigure the output states into an arbitrary point on a higher-order Poincaré sphere based on in-plane interference of two guided waves. Our approach provides a promising solution to generate and manipulate the HOPBs in a compact manner, which would be further enhanced by employing the electro-optical modulation on a lithium niobate waveguide to access a fully tunable scheme.

Advances in Meta-Optics and Metasurfaces: Fundamentals and Applications

Meta-optics based on metasurfaces that interact strongly with light has been an active area of research in recent years. The development of meta-optics has always been driven by human's pursuits of the ultimate miniaturization of optical elements, on-demand design and control of light beams, and processing hidden modalities of light. Underpinned by meta-optical physics, meta-optical devices have produced potentially disruptive applications in light manipulation and ultra-light optics. Among them, optical metalens are most fundamental and prominent meta-devices, owing to their powerful abilities in advanced imaging and image processing, and their novel functionalities in light manipulation. This review focuses on recent advances in the fundamentals and applications of the field defined by excavating new optical physics and breaking the limitations of light manipulation. In addition, we have deeply explored the metalenses and metalens-based devices with novel functionalities, and their applications in computational imaging and image processing. We also provide an outlook on this active field in the end.