공수현 교수

Nanoscale chiral valley-photon interface Occupation of different valleys within the band structure of some materials can be used to encode information. That information is typically encoded in terms of the chirality or polarization of emitted photons. Gong et al. combined a plasmonic silver nanowire with a flake of the transition metal dichalcogenide WS 2 to form a nanophotonic platform for the transfer of solid-state spin into optical information over mesoscopic distances. The direction of ligh

The hybrid nature of exciton polaritons opens up possibilities for developing a new concept nonlinear photonic device (e.g., polariton condensation, switching, and transistor) with great potential for controllability. Here, we proposed a novel type of polariton system resulting from strong coupling between a two-dimensional exciton and whispering gallery mode photon using a core-shell GaN/InGaN hexagonal wire. High quality, nonpolar InGaN multiple-quantum wells (MQWs) were conformally formed on

The quantum plasmonics field has emerged and been growing increasingly, including study of single emitter-light coupling using plasmonic system and scalable quantum plasmonic circuit. This offers opportunity for the quantum control of light with compact device footprint. However, coupling of a single emitter to highly localized plasmonic mode with nanoscale precision remains an important challenge. Today, the spatial overlap between metallic structure and single emitter mostly relies either on c

Valley pseudospin has emerged as a good quantum number to encode information, analogous to spin in spintronics. Two-dimensional transition metal dichalcogenides (2D TMDCs) recently attracted enormous attention for their easy access to the valley pseudospin through valley-dependent optical transitions. Different ways have been reported to read out the valley pseudospin state. For practical applications, on-chip access to and manipulation of valley pseudospins is paramount, not only to read out bu

Anodic aluminum oxide (AAO) films with different pore sizes were prepared to modulate the effective refractive index and birefringence. To investigate the relationship between the refractive index and the pore size of the AAO film, optical constants were obtained using a prism coupler with various lasers. With experimental results, the dispersion curve of alumina itself without pores was extracted using a theoretical anisotropic model. We demonstrated that AAO films could offer a wide range of r

Abstract The strong excitonic properties of transition metal dichalcogenides (TMD) have led to the successful demonstration of exciton‐polaritons (EPs) in various optical cavity structures. Recently, self‐hybridized EPs have been discovered in a bare TMD layer, but experimental investigation is still lacking because of their nonradiative nature. Herein, the direct observation of self‐hybridized EPs in a bare multilayer WS 2 via the evanescent field coupling technique is reported. Because of the

Abstract An ultra‐thin transition metal dichalcogenide (TMDC) layer can support guided exciton‐polariton modes due to the strong coupling between excitons and photons. Herein, we report the guided mode resonance in an ultra‐thin TMDC grating structure. Owing to the strong exciton resonances in TMDCs, a TMDC grating structure shows guided‐mode resonance even at a thickness limit of ∼10 nm and is capable of realizing polaritonic dispersion in a monolithic grating structure. We investigated the pol

Excitons, electron–hole pairs in semiconductors, can be utilized as information carriers with a spin or valley degree of freedom. However, manipulation of excitons’ motion is challenging because of their charge-neutral characteristic and short recombination lifetimes. Here we demonstrate electric-field-driven drift and funneling of charged excitons (i.e., trions) toward the center of a MoSe 2 monolayer. Using a simple bottom-gate device, we control the electric fields in the vicinity of the susp

Abstract Light confinement to sub‐wavelength scales is actively studied for nanophotonic applications because it gives rise to intriguing optical properties with enhanced light‐matter interaction. Herein, an ultrathin exciton–polariton waveguide based on a WS 2 multilayer is proposed for sub‐wavelength light guiding. A WS 2 waveguide supports guided exciton–polariton modes even with a few tens of nanometers of thickness. It is theoretically confirmed that the WS 2 waveguide has significantly low

Abstract With the rapid emergence of artificial intelligence (AI) technology and the exponential growth in data generation, there is an increasing demand for high-performance and highly integratable optical modulators. In this work, we present an ultra-compact exciton-polariton Mach–Zehnder (MZ) modulator based on WS 2 multilayers. The guided exciton-polariton modes arise in an ultrathin WS 2 waveguide due to the strong excitonic resonance. By locally exciting excitons using a modulation laser i

Although the study of single quantum dot (QD) properties without the background noise and dephasing processes caused by surrounding carriers is a crucial issue, the spatial-selective excitation of a single QD is still challenging, due to the diffraction nature of light. Here, we demonstrate a deep subwavelength excitation of a single QD using two-photon plasmonic nanofocusing. Self-aligned plasmonic nanofocusing on a single QD was achieved using metal coated nanopyramid structures. The highly en

Abstract Guided exciton–polariton modes naturally exist in bare transition metal dichalcogenide (TMDC) layers due to self‐hybridization between excitons and photons. However, these guided polariton modes exhibit a limited propagation distance owing to the substantial exciton absorption within the material. Here, we investigated the impact of hexagonal boron nitride (hBN) layers on guided exciton–polariton modes in WS 2 multilayers. By integrating hBN layers, we demonstrate a notable enhancement

The transverse nature of light leads to longitudinal optical spin. Here, the unprecedented transverse optical spin of propagating waves and guided modes in a gyroelectric medium is clarified. We identify the propagation modes in a bulk gyroelectric medium and their polarization in terms of optical spin. The anisotropic permittivity of a gyroelectric medium results in two propagation modes, slow and fast, in which the optical spin varies according to the propagation direction. When the magnetizat