arXiv subjects

Hyeonhee Kim

Publications and source records attributed to Hyeonhee Kim.

3 recordsLinked to original sources

arXiv2025

Arbitrary Total Angular Momentum Vectorial Holography Using Bi-Layer Metasurfaces

Advanced holographic techniques are increasingly demanded for high-capacity and secure information processing. In this context, orbital angular momentum (OAM) stands out as a powerful resource for optical multiplexing, offering access to an unbounded set of orthogonal modes. To harness this potential, metasurfaces, with their considerable ability to control light, have emerged as key platforms for OAM-multiplexed holography. Nevertheless, conventional OAM holography suffers from limited polarization engineering capabilities due to the lack of chirality control in single-layer metasurfaces. Here, we introduce a bi-layer metasurface architecture that realizes total angular momentum (TAM) vectorial holography, where TAM represents the combination of spin angular momentum (SAM, equivalent to polarization) and OAM of light. In contrast to previous approaches, this scheme enables true polarization-OAM multiplexing, facilitating the independent generation of vectorial holographic images for each orthogonal TAM input state. This concept is validated numerically and experimentally, confirming the feasibility of TAM vectorial holography. The proposed scheme can be easily integrated with other recent holography generation approaches, such as vector beam multiplexing and bidirectional holography, thereby further expanding its multiplexing capability. This work establishes a versatile framework for advanced full-vectorial holography, showing how metasurfaces can unlock multiplexing strategies for emerging photonic systems.

physics.optics↗

arXiv2024

Bidirectional Vectorial Holography Using Bi-Layer Metasurfaces and Its Application to Optical Encryption

The study of optical systems with asymmetric responses has grown significantly due to their broad application potential in various fields. In particular, Janus metasurfaces are notable for their ability to control light asymmetrically at the pixel level within thin films. However, previous demonstrations were restricted to the partial control of asymmetric transmission for a limited set of input polarizations, focusing primarily on scalar functionalities. Here, we introduce optical metasurfaces consisting of bi-layer silicon nanostructures that can achieve a fully generalized form of asymmetric transmission for any possible input polarization. Their designs owe much to our theoretical model of asymmetric optical transmission in reciprocal systems that explicates the relationship between front- and back-side Jones matrices for general cases, revealing a fundamental correlation between the polarization-direction channels of opposing sides of incidence. To practically circumvent this constraint, we propose a method to partition transmission space, enabling the realization of four distinct vector functionalities within the target volume. As a proof of concept, we experimentally demonstrate polarization-direction-multiplexed Janus vector holograms generating four vector holograms. When integrated with computational vector polarizer arrays, this approach facilitates optical encryption with a high level of obscurity. We anticipate that our mathematical framework and novel material systems for generalized asymmetric transmission may pave the way for applications such as optical computations, sensing, and imaging.

physics.optics↗

arXiv2022

Universal metasurfaces for complete linear control of coherent light transmission

Recent advances in metasurfaces and optical nanostructures have enabled complex control of incident light with optically thin devices. However, it has thus far been unclear whether it is possible to achieve complete linear control of coherent light transmission, i.e., independent control of polarization, amplitude, and phase for both input polarization states, with just a single, thin nanostructure array. Here we prove that it is possible and propose a universal metasurface, a bilayer array of high-index elliptic cylinders, that possesses a complete degree of optical freedom with fully designable chirality and anisotropy. We mathematically show the completeness of achievable light control with corresponding Jones matrices, experimentally demonstrate new types of three-dimensional holographic schemes that were formerly impossible, and present a systematic way of realizing any input-state-sensitive vector linear optical device. Our results unlock previously inaccessible degrees of freedom in light transmission control.

physics.optics↗