Jongwon Lee

Electrically tunable mid‐infrared metasurfaces with nanosecond response time and broad tuning range are reported. Electrical tuning is achieved by employing strong polaritonic coupling of electromagnetic modes in metallic nanoresonators with voltage‐tunable inter‐subband transitions in semiconductor heterostructures, tailored for a giant quantum‐confined Stark effect. Experimentally, a 220‐nm‐thick multi‐quantum‐well semiconductor layer is sandwiched between a ground plane and a metal layer patt

Ultrathin metasurfaces with record-high nonlinear optical response of 1.2 × 106 pm V−1 for second harmonic generation are experimentally demonstrated in the mid-infrared spectral range. A second harmonic power conversion efficiency of 0.075% is achieved in a 400-nm-thick (λ/25) metasurface at a pump intensity of only 15 kW cm−2. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized f

Abstract Lithium (Li) metal is regarded as the most attractive anode material for high‐energy Li batteries, but it faces unavoidable challenges—uncontrollable dendritic growth of Li and severe volume changes during Li plating and stripping. Herein, a porous carbon framework (PCF) derived from a metal–organic framework (MOF) is proposed as a dual‐phase Li storage material that enables efficient and reversible Li storage via lithiation and metallization processes. Li is electrochemically stored in

Nonlinear metasurfaces are advancing into a new paradigm of "flat nonlinear optics" owing to the ability to engineer local nonlinear responses in subwavelength-thin films. Recently, attempts have been made to expand the design space of nonlinear metasurfaces through nonlinear chiral responses. However, the development of metasurfaces that display both giant nonlinear circular dichroism and significantly large nonlinear optical response is still an unresolved challenge. Herein, we propose a metho

Abstract Orbital angular momentum (OAM) has received considerable attention regarding high‐capacity communication owing to its spatial orthogonality. However, it is still challenging to build a compact communication system that can generate multiple coaxial OAM beams and receive information from each. In this work, OAM multiplexing and demultiplexing at the E‐band frequency using a single metasurface structure is proposed and experimentally demonstrated. For OAM multiplexing, the metasurface use

Surface-enhanced infrared absorption (SEIRA) spectroscopy is a powerful methodology for sensing and identifying small quantities of analyte molecules via coupling between molecular vibrations and an enhanced near-field induced in engineered structures. A metamaterial absorber (MA) is proposed as an efficient SEIRA platform; however, its efficiency is limited because it requires the appropriate insulator thickness and has a limited accessible area for sensing. SEIRA spectroscopy is proposed using

Abstract Nonlinear responses in metasurfaces have shown great promise for various applications, such as nonlinear holography, spectroscopy, and novel nonlinear light sources. Metasurfaces that produce nonlinear responses have the advantage of greatly relaxed phase‐matching conditions, which can simplify nonlinear optical systems. However, the practical use of nonlinear metasurfaces with an accessible optical pump source requires giant nonlinear responses. A multi‐quantum‐well‐loaded nonlinear me

Vortex beams carrying orbital angular momentum (OAM) have attracted considerable attention for the development of high-capacity wireless communication systems due to their infinite sets of orthogonal modes. However, the practical applications of Laguerre-Gaussian type vortex beams are limited due to the fact that the divergence angle increases as the order of the OAM mode increases. In this work, we present metasurfaces that generate vortex beams carrying OAM modes with reduced divergence angles

Electrically reconfigurable metasurfaces that overcome the static limitations in controlling the fundamental properties of scattered light are opening new avenues for functional flat optics. This work proposes and experimentally demonstrates electrically phase-tunable mid-infrared metasurfaces based on the polaritonic coupling of Stark-tunable intersubband transitions in semiconductor heterostructures and electromagnetic modes in plasmonic nanoresonators. In the applied voltage range of -3 to +3

Abstract We report a sensing platform for surface-enhanced infrared absorption (SEIRA) spectroscopy, based on Fano metamaterials (FMMs) on dielectric nanopedestals. FMMs consist of two parallel gold (Au) nanorod antennas, with a small horizontal coupler attached to one of the nanorod antenna. When placed on SiO 2 dielectric nanopedestals, which exhibit strong field enhancements caused by the interference between subradiant and superradiant plasmonic resonances, they provide the highly enhanced E

Abstract Nonlinear intersubband polaritonic metasurfaces, which integrate giant nonlinear responses derived from intersubband transitions of multiple quantum wells (MQWs) with plasmonic nanoresonators, not only facilitate efficient frequency conversion at pump intensities on the order of few tens of kW cm -2 but also enable electrical modulation of nonlinear responses at the individual meta-atom level and dynamic beam manipulation. The electrical modulation characteristics of the magnitude and p

Abstract Metasurfaces that generate nonlinear optical responses provide new degrees of freedom for applications such as nonlinear holography, wave mixing, and new frequencies generation. To extend the utility of flat nonlinear optics, metasurfaces providing both giant nonlinear response for efficient frequency mixing in subwavelength films and a single‐beam output with a local wavefront control need to be developed. Metasurfaces with giant nonlinear response have recently been realized using the