Hwi Kim

Bio: Hwi Kim is an academic researcher from Korea University. The author has contributed to research in topics: Holography & Surface plasmon. The author has an hindex of 32, co-authored 243 publications receiving 4697 citations. Previous affiliations of Hwi Kim include Korea University Sejong Campus & Seoul National University.

Three-dimensional display technologies of recent interest: principles, status, and issues [Invited]

Abstract: Recent trends in three-dimensional (3D) display technologies are very interesting in that both old-fashioned and up-to-date technologies are being actively investigated together. The release of the first commercially successful 3D display product raised new research topics in stereoscopic display. Autostereoscopic display renders a ray field of a 3D image, whereas holography replicates a wave field of it. Many investigations have been conducted on the next candidates for commercial products to resolve existing limitations. Up-to-date see-through 3D display is a concept close to the ultimate goal of presenting seamless virtual images. Although it is still far from practical use, many efforts have been made to resolve issues such as occlusion problems.

Synthesis and Dynamic Switching of Surface Plasmon Vortices with Plasmonic Vortex Lens

Abstract: The generation of surface plasmon vortices with arbitrary higher order vortex topological charges with novel plasmonic vortex lens is experimentally demonstrated. It is shown that the polarization sensitivity of the plasmonic vortex lens can be utilized for the dynamic switching of the surface plasmon vortices with different topological charges. A simple algebraic rule related to the vortex topological charge change in the dynamic switching is formulated, and its proof is provided with theory and experiment. The synthesis and dynamic switching of higher order surface plasmon vortices have profound potential in optical trapping, optical data storage, and other related fields.

Metasurface eyepiece for augmented reality

Abstract: Recently, metasurfaces composed of artificially fabricated subwavelength structures have shown remarkable potential for the manipulation of light with unprecedented functionality. Here, we first demonstrate a metasurface application to realize a compact near-eye display system for augmented reality with a wide field of view. A key component is a see-through metalens with an anisotropic response, a high numerical aperture with a large aperture, and broadband characteristics. By virtue of these high-performance features, the metalens can overcome the existing bottleneck imposed by the narrow field of view and bulkiness of current systems, which hinders their usability and further development. Experimental demonstrations with a nanoimprinted large-area see-through metalens are reported, showing full-color imaging with a wide field of view and feasibility of mass production. This work on novel metasurface applications shows great potential for the development of optical display systems for future consumer electronics and computer vision applications.

Wide viewing angle dynamic holographic stereogram with a curved array of spatial light modulators

Abstract: A novel design of dynamic holographic stereogram with a curved array of spatial light modulators (SLMs) is proposed. In general, it is difficult to simultaneously achieve a wide viewing angle and an available width for the digital holographic display. Moreover, the wide viewing angle of a display system needs a large optical numerical aperture where the paraxial approximation fails, and thus an extremely large planar SLM is necessary in using previous methods. To solve this problem, our proposed display system is composed of a curved array of SLMs to obtain a large number of data points and reduce the spatial bandwidth in SLMs. In the curved array of SLMs, each SLM is individually transformed to display local angular spectra of object wave, which is based on a fundamental idea of holographic stereogram. To embody the dynamic holographic stereogram with SLMs, each SLM is effectively reformed for simplifying the optical structure and reducing the light power loss. In detail, spatially modulated wave is optically divided and transformed, as if each SLM were composed of three sub-SLMs. This design improves the scalability in viewing angle of holographic display and the loss of light power is significantly reduced. With this method, we can achieve the digital holographic display with 22.8 degrees viewing angle.

Complete amplitude and phase control of light using broadband holographic metasurfaces

Abstract: Reconstruction of light profiles with amplitude and phase information, called holography, is an attractive optical technology with various significant applications such as three-dimensional imaging and optical data storage. Subwavelength spatial control of both amplitude and phase of light is an essential requirement for an ideal hologram. However, traditional holographic devices suffer from their restricted capabilities of incomplete modulation in both amplitude and phase of visible light; this results in sacrifice of optical information and undesirable occurrences of critical noises in holographic images. Herein, we have proposed a novel metasurface that is capable of completely controlling both the amplitude and phase profiles of visible light independently with subwavelength spatial resolution. The full, continuous, and broadband control of both amplitude and phase was achieved using X-shaped meta-atoms based on the expanded concept of the Pancharatnam-Berry phase. The first experimental demonstrations of the complete complex-amplitude holograms with subwavelength definition at visible wavelengths were achieved, and excellent performances with a remarkable signal-to-noise ratio as compared to those of traditional phase-only holograms were obtained. Extraordinary control capability with versatile advantages of our metasurface paves a way to an ideal holography, which is expected to be a significant advancement in the field of optical holography and metasurfaces.

Photonic crystals

Abstract: The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

Introduction to the Finite Element Method

Abstract: This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems. Although we discuss the main points in the application of the finite element method to electromagnetic design, including formulation and implementation, those who seek deeper understanding of the finite element method should consult some of the works listed in the bibliography section.

Spin-orbit interactions of light

Abstract: This Review article provides an overview of the fundamental origins and important applications of the main spin–orbit interaction phenomena in modern optics that play a crucial role at subwavelength scales. Light carries both spin and orbital angular momentum. These dynamical properties are determined by the polarization and spatial degrees of freedom of light. Nano-optics, photonics and plasmonics tend to explore subwavelength scales and additional degrees of freedom of structured — that is, spatially inhomogeneous — optical fields. In such fields, spin and orbital properties become strongly coupled with each other. In this Review we cover the fundamental origins and important applications of the main spin–orbit interaction phenomena in optics. These include: spin-Hall effects in inhomogeneous media and at optical interfaces, spin-dependent effects in nonparaxial (focused or scattered) fields, spin-controlled shaping of light using anisotropic structured interfaces (metasurfaces) and robust spin-directional coupling via evanescent near fields. We show that spin–orbit interactions are inherent in all basic optical processes, and that they play a crucial role in modern optics.

Light passing through subwavelength apertures

Abstract: This review provides a perspective on the recent developments in the transmission of light through subwavelength apertures in metal films. The main focus is on the phenomenon of extraordinary optical transmission in periodic hole arrays, discovered over a decade ago. It is shown that surface electromagnetic modes play a key role in the emergence of the resonant transmission. These modes are also shown to be at the root of both the enhanced transmission and beaming of light found in single apertures surrounded by periodic corrugations. This review describes both the theoretical and experimental aspects of the subject. For clarity, the physical mechanisms operating in the different structures considered are analyzed within a common theoretical framework. Several applications based on the transmission properties of subwavelength apertures are also addressed.

Creation of a needle of longitudinally polarized light in vacuum using binary optics

Abstract: Light is often thought of in terms of radial polarization, but longitudinal polarization is also possible, and it has some intriguing possibilities for particle acceleration. Binary optics, combined with a high-numerical-aperture lens, is a potential route to achieving light with this unusual property.