Jaehyuck Jang

The development of real-time and sensitive humidity sensors is in great demand from smart home automation and modern public health. We hereby proposed an ultrafast and full-color colorimetric humidity sensor that consists of chitosan hydrogel sandwiched by a disordered metal nanoparticle layer and reflecting substrate. This hydrogel-based resonator changes its resonant frequency to external humidity conditions because the chitosan hydrogels are swollen under wet state and contracted under dry st

Metasurfaces made up of subwavelength arrays of Mie scatterers can be engineered to control the optical properties of incident light. The hybridization of the fundamental Mie resonances with lattice resonances greatly enhances the scattering cross-section of individual Mie scatterers. Through careful design of the locations of these hybridized modes using two differently engineered hydrogenated amorphous silicon nanorods, we numerically calculate and experimentally fabricate two examples of full

Abstract A tunable Fabry–Pérot resonator is realized using metal–insulator–metal structure, in which the insulator is chitosan hydrogel. The chitosan swells in response to changes in relative humidity; this change affects transmissive structural color of the multilayer structure. This tunable resonator is utilized for a humidity sensor combined with a photovoltaic cell. The change in current through the photovoltaic cell provides rapid precise measurement of relative humidity, and the change in

Abstract High‐quality and tunable structural color printing with feasible fabrication is a key goal in recent decades, holding the possibility for full‐color microdisplay and impeccable cryptographic nanoprints. Plasmonic approach suffers from the inevitable material absorption restricting the color spectrum with suppressed lightness. Recent progress in dielectric nanophotonics offers low‐loss solution for color rendering, but dynamic functionality is still in infancy of changing colors with unc

The hybridised resonances between Mie-scatterers and lattice resonances, i.e. quasi-guided mode resonances, are investigated. The scattering of the Mie-resonators is improved by the first order of transmitted diffracted light which is coupled to the lattice formed by the Mie-resonators. The conditions of coupling are dependent on the refractive index of the substrate and the effective refractive index of the unit cell of the resonators. Based on the momentum matching conditions, the cut-off wave

In article number 1801070, Junsuk Rho and co-workers realize polarization-encrypted nanoprints by tunable structural coloring with a combination of symmetric and asymmetric nanoantennas. The polarization-encrypted nanoprints designed based on Kerker's condition are decrypted under a certain polarization angle of incident light. The demonstration of the nanoprints expands the scope of metasurfaces toward novel security technologies, and thus further shows their potential for integration with smar

Abstract The field of high-bandwidth holography has been extensively studied over the past decade. Orbital angular momentum (OAM) holography, which utilizes vortex beams with theoretically unbounded OAM modes as information carriers, showcases the large capacitance of hologram storage. However, OAM holography has been limited to a single wavelength, restricting its potential for full-color holography and displays. In this study, we propose wavelength and OAM multiplexed holography that utilizes

Low-dimensional light-emitting materials have been actively investigated due to their unprecedented optical and optoelectronic properties that are not observed in their bulk forms. However, the emission from low-dimensional light-emitting materials is generally weak and difficult to use in nanophotonic devices without being amplified and engineered by optical cavities. Along with studies on various planar optical cavities over the last decade, the physics of cavity-emitter interactions as well a

The complex degrees of freedom of light, such as amplitude, phase, polarization, and orbital angular momentum, make it a prime candidate for use in optical security and encryption. By exploiting the unique characteristics of metasurfaces, exciting new optical security platforms have been demonstrated.

We introduced tunable Fabry-Pérot resonator using metal-insulator-metal multilayer, in which the insulator is hydrogel foam of chitosan [1]. The chitosan, one of polysaccharide, is responsive to external humidity, so the thickness and refractive index of chitosan change in response to relative humidity (RH); this trait can be utilized to tune resonance wavelegths of the resonator. This tunable color filter can function as humidity sensor when incorporated with photovoltaic (PV) cell. The PV cell

In recent years, the field of quantum nanophotonics has been thriving with an intense interest in the development of new theories, devices, and applications for specific uses.This special issue on "Quantum nanophotonics" highlights some recent developments in this topic through reviews, perspectives, and research papers.This issue contains review and perspective articles that provide a comprehensive overview of cutting-edge topics.Chang and Zwiller [1] review the recent progresses in integrated

In article number 1901932, Inkyu Park, Junsuk Rho and co-workers introduce a tunable Fabry–Pérot resonator that has metal–(chitosan-based hydrogel)–metal structure. The chitosan swells in response to changes in relative humidity; this change affects transmissive structural color of the multilayer structure. As demonstration, this tunable resonator is utilized for a real-time colorimetric humidity sensor combined with a photovoltaic cell, which can lead to development of a self-powered sensor.

In our study, we introduce wavelength-multiplexed orbital angular momentum meta-holography, aiming to expand holographic information channels by leveraging light's wavelength and orbital angular momentum (OAM). We selectively employed red, green, and blue as primary colors, and incorporated four unique OAM channels (-2, -1, 1, and 2). Through the utilization of a metasurface comprising three distinct types of wavelength-selective meta-atoms, we successfully encoded the twelve holographic images

The eye tracking technology is widespread all around the society, and is demonstrating great performances in both preciseness and convenience. Hereby we can glimpse new possibility of an interface’s conduct without screen-touching. This technology can become a new way of conversation for those including but not limited to the patients suffering from Lou Gehrig’s disease, who are paralyzed each part by part of the body and finally cannot help but only moving eyes. Formerly in that case, the patie

We investigated amplified scattering of low-index Mie-resonators using guided-mode resonance from lattice. The diffracted light into first order is coupled to the lattice, thereby boosting the scattering of gallium nitride (GaN) nanopillars. This momentum matching condition is bounded by refractive index of substrate and effective refractive index of the GaN pillars. The effective refractive index is determined by the filling ratio of the GaN pillar inside a specific periodicity of unit cell. By