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52. Additional file 1 of Self-assembled pagoda-like nanostructure-induced vertically stacked split-ring resonators for polarization-sensitive dichroic responses

Author

Kim, Sanghoon, Jung, Chunghwan, Mun, Jungho, Kim, Mooseong, Yoon, Hyeongkeon, Jang, Junho, Go, Myeongcheol, Lee, Jaeyong, Rho, Junsuk, and Kim, Jin Kon

Abstract

Additional file 1: Figure S1. Top-view (top, i) and 70° tilted-view (bottom, ii) SEM images of AAO template with various diameters (D) and height (H) is (a) 30 nm, 200 nm (b) 50 nm, 200 nm and (c) 100 nm, 300 nm. Figure S2. FE-SEM images with energy dispersive spectroscopy (EDS) results (a) before and (b) after tilt silver deposition. The EDS peak of silver at around 3.0 keV confirms the presence of silver element. Figure S3. (a) A photograph of a sample. (b) Top-view FE-SEM images of a high-density array of nanorods (inset is a expanded image) and (c) diameter of SSRR nanostructure at the four position over a large area (3 × 3 cm2). Figure S4. Simulated reflection spectrum of SSRRs with (a) uniformly deposited Ag film and (b) island-like discretely deposited Ag (Radius = 20 nm and island spacing distance = 10 nm). Black solid line: Reflectance under x-polarized light. Red solid line: Reflectance under y-polarized light. Blue dash line: The difference between x- and y- polarized light. Figure S5. Simulated reflection spectrum of (a) vertically erected SSRR and (b) tilted SSRR (Tilt angle = 20°). Black solid line: Reflectance under x-polarized light. Red solid line: Reflectance under y-polarized light. Blue dash line: The difference between x- and y- polarized light. Figure S6. Effective optical parameters of SSRR under y-polarized light. Effective (a) wave impedance, (b) permittivity, and (c) permeability of SSRR. Figure S7. Effective optical parameters (Z, ε, and μ) of the SSRR substructure come from S-parameter retrieval method. (a) Schematic image and inclusion relationship table for each substructure. (b) Effective wave impedance, (c) permittivity, and (d) permeability under x-polarized light. Figure S8. Effect of (a) the center-to-center distance between nanorods a, (b) the nanorod diameter d, (c) the number of ring N, and (d) neighboring inter-rod distance Lo on the reflectance differences between x- and y-polarized light (Rx-Ry). Figure S9 (a) Schematic image of a hexagonal array of SSRR (a: the center-to-center distance between two neighboring nanorods). (b) Experimentally measured reflectance of the array of SSRR. FE-SEM image of a low-density array of (c) pagoda-like nanorods (d) SSRR with large perodicity (a = 500 nm).

Published
2022
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53. Intrachain Delocalization Effect of Charge Carriers on the Charge-Transfer State Dynamics in Organic Solar Cells

Author

Lee, Dongki, primary, Lee, Jaewon, additional, Sin, Dong Hun, additional, Han, Se Gyo, additional, Lee, Hansol, additional, Choi, Wookjin, additional, Kim, Hyojung, additional, Noh, Jaebum, additional, Mun, Jungho, additional, Sung, Woong, additional, Kim, Sang Woo, additional, Jeong, Byeong Geun, additional, Kim, Sung Hyuk, additional, Rho, Junsuk, additional, Jeong, Mun Seok, additional, and Cho, Kilwon, additional

Published
2022
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54. Inducing and Probing Localized Excitons in Atomically Thin Semiconductors via Tip‐Enhanced Cavity‐Spectroscopy (Adv. Funct. Mater. 33/2021)

Author

Lee, Hyeongwoo, primary, Kim, Inki, additional, Park, Chulho, additional, Kang, Mingu, additional, Choi, Jinseong, additional, Jeong, Kwang‐Yong, additional, Mun, Jungho, additional, Kim, Yeseul, additional, Park, Jeonghoon, additional, Raschke, Markus B., additional, Park, Hong‐Gyu, additional, Jeong, Mun Seok, additional, Rho, Junsuk, additional, and Park, Kyoung‐Duck, additional

Published
2021
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55. Charge Recycling Mechanism Through a Triplet Charge-Transfer State in Ternary-Blend Organic Solar Cells Containing a Nonfullerene Acceptor

Author

Lee, Dongki, primary, Hwang, Hyeongjin, additional, Sin, Dong Hun, additional, Park, Chaneui, additional, Han, Se Gyo, additional, Mun, Jungho, additional, Noh, Jaebum, additional, Kim, Sung Hyuk, additional, Kim, Hyojung, additional, Lee, Hansol, additional, Lee, Chanwoo, additional, Rho, Junsuk, additional, Cho, Kilwon, additional, and Jeong, Mun Seok, additional

Published
2021
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60. Backward Phase-Matched Second-Harmonic Generation from Stacked Metasurfaces

Author

Stolt, Timo, primary, Kim, Jeonghyun, additional, Héron, Sébastien, additional, Vesala, Anna, additional, Yang, Younghwan, additional, Mun, Jungho, additional, Kim, Minkyung, additional, Huttunen, Mikko. J., additional, Czaplicki, Robert, additional, Kauranen, Martti, additional, Rho, Junsuk, additional, and Genevet, Patrice, additional

Published
2021
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62. Development of advanced radiation sources at KAERI

Author

Lee, Kitae, Jeong, Young Uk, Park, Seong Hee, Jang, Kyu-Ha, Miginsky, S. V., Gudkov, B. A., Cha, Yong-Ho, Mun, Jungho, Kim, Kyung Nam, Kim, Ha-Na, Park, Sun Jeong, Han, Byung-Heon, Bae, Sangyoon, Kim, Hyunwoo, and Vinokurov, N. A.

Published
2013
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72. A Compact THz FEL at KAERI: the Project and the Status

Author

Miginsky, Sergey, Bae, Sangyoon, Gudkov, Boris, Jang, Kyu Ha, Jeong, Young Uk, Lee, Kitae, Mun, Jungho, Park, Seong Hee, and Setiniyaz, Sadiq

Subjects
New Lasing & Status of Projects, Accelerator Physics
Abstract

A new compact THz free electron laser driven by a microtron is being recently developed at KAERI. It uses a hybrid electromagnetic undulator. A novel scheme of injection/extraction/outcoupling is developed. The machine is partially assembled and commissioned. Characteristic features and current state are described in the paper., Proceedings of the 38th Int. Free Electron Laser Conf., FEL2017, Santa Fe, NM, USA

Published
2018
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77. Near-zero reflection of all-dielectric structural coloration enabling polarization-sensitive optical encryption with enhanced switchability.

Author

Jung, Chunghwan, Yang, Younghwan, Jang, Jaehyuck, Badloe, Trevon, Lee, Taejun, Mun, Jungho, Moon, Seong-Won, and Rho, Junsuk

Subjects
OPTICAL polarization, VISIBLE spectra, COLOR printing, TWO-dimensional bar codes, MAGNETIC fields, ENCRYPTION protocols
Abstract

Structural coloration using metasurfaces has been steadily researched to overcome the limitations of conventional color printing using pigments by improving the resolution, lowering the toxicity, and increasing the durability. Many metasurfaces have been demonstrated for dynamic structural coloration to convert images at the visible spectrum. However, the previous works cannot reach near-zero scattering when colors are turned-off, preventing it from being cryptographic applications. Herein, we propose a completely on/off switchable structural coloration with polarization-sensitive metasurfaces, enabling full-colored images to be displayed and hidden through the control of the polarization of incident light. It is confirmed that the nanostructure exhibits the polarization-dependent magnetic field distributions, and near-zero scattering is realized when the polarization of incident light is perpendicular to the long axis of the nanofins. Also, the metasurfaces are made up of triple-nanofin structures whose lengths affect locations of resonance peaks, resulting in full-color spectrum coverages. With such advantages, a QR code image, a two-color object image, and an overlapped dual-portrait image are obtained with the metasurfaces. Such demonstrations will provide potential applications in the fields of high-security information encryption, security tag, multichannel imaging, and dynamic displays. [ABSTRACT FROM AUTHOR]

Published
2021
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78. Metasurfaces-Based Absorption and Reflection Control: Perfect Absorbers and Reflectors

Author

Badloe, Trevon, Mun, Jungho, and Rho, Junsuk

Subjects
Article Subject, Physics::Optics
Abstract

In the past decade, the realisation of negative index materials has initiated extensive research into metamaterials. Perfect absorbers and reflectors are of particular interest as their usefulness is endless in a range of different fields and devices. Since it was originally shown that a device can achieve unity absorption of electromagnetic waves, it has become a hot area of research to develop perfect absorbers based on polarisation independence and incident angle independence, at a range of frequencies from microwave to optical ones. The amazing performance, flexibility, and tunability of these metamaterials will be discussed here, by presenting the different designs and working mechanisms that have been realised up to now. Their limitations and shortcomings will be addressed and future plans for perfect absorbers and reflectors will be suggested.

Published
2017
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83. Smart SERS Hot Spots: Single Molecules Can Be Positioned in a Plasmonic Nanojunction Using Host–Guest Chemistry

Author

Kim, Nam Hoon, primary, Hwang, Wooseup, additional, Baek, Kangkyun, additional, Rohman, Md. Rumum, additional, Kim, Jeehong, additional, Kim, Hyun Woo, additional, Mun, Jungho, additional, Lee, So Young, additional, Yun, Gyeongwon, additional, Murray, James, additional, Ha, Ji Won, additional, Rho, Junsuk, additional, Moskovits, Martin, additional, and Kim, Kimoon, additional

Published
2018
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86. Singlet Exciton Delocalization in Gold Nanoparticle-Tethered Poly(3-hexylthiophene) Nanofibers with Enhanced Intrachain Ordering

Author

Lee, Dongki, primary, Sin, Dong Hun, additional, Kim, Sang Woo, additional, Lee, Hansol, additional, Byun, Hye Ryung, additional, Mun, Jungho, additional, Sung, Woong, additional, Kang, Boseok, additional, Kim, Dae Gun, additional, Ko, Hyomin, additional, Song, Sung Won, additional, Jeong, Mun Seok, additional, Rho, Junsuk, additional, and Cho, Kilwon, additional

Published
2017
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88. Stabilization of Magnetron Frequency for a Microtron-Driven FEL

Author

Gudkov, Boris, Bae, Sangyoon, Jang, Kyu Ha, Jeong, Young Uk, Kim, Hyun Woo, Lee, Kitae, Miginsky, Sergey, Mun, Jungho, Park, Seong Hee, Shim, Gyu Il, and Vinokurov, Nikolay

Subjects
Physics::Accelerator Physics, FEL Technology and HW: Electron Diagnostics, Timing, Synchronization, and Controls, Accelerator Physics
Abstract

Under KAERI WCI program we develop a compact pulsed microtron-driven FEL. Electron bunches trains are accelerated in the microtron and transported by the beamline to the undulator. The RF cavity in the microtron is fed by a magnetron. Any accelerator driver for a FEL should provide an electron beam having very stable parameters such as electron energy, current, and especially the bunch repetition rate in a train. All mentioned parameters depend on magnetron current. It means that special attention should be paid for the shape of the current pulse, supplied to the magnetron from the modulator. We developed the modulator project with a computer control that will provide an arbitrary shape of the magnetron current. A simplified prototype was fabricated and tested. The methods of controlling of the pulse shape are considered. Simulation and experimental results are presented., Proceedings of the 37th International Free Electron Laser Conference, FEL2015, Daejeon, Republic of Korea

Published
2015
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89. Waveguide THz FEL Oscillators

Author

Miginsky, Sergey, Bae, Sangyoon, Gudkov, Boris, Jang, Kyu Ha, Jeong, Young Uk, Kim, Hyun Woo, Lee, Kitae, Mun, Jungho, Park, Seong Hee, Shim, Gyu Il, and Vinokurov, Nikolay

Subjects
Physics::Accelerator Physics, Physics::Optics, FEL Oscillator, Accelerator Physics
Abstract

In today's world there is a significant demand for FEL-based THz radiation sources. They have a wide tuning range, a narrow band of radiation, and comparably high peak and average emission power. There are a significant number of these machines in the world, operating or in the development. The main difference between a long-wave FEL, of THz or a millimeter band, and a conventional one is a too big transverse size of the fundamental mode of an open optical resonator. It claims a large gap in an undulator that dramatically decreases its strength. Both factors sorely decrease the amplification and the efficiency, and often make lasing impossible. The main way to solve this problem is to use a waveguide optical resonator. It decreases and controls the transverse size of the fundamental mode. However, the waveguide causes a number of problems: power absorption in its walls; higher modes generation by inhomogeneities, as it is not ideal; electron beam injection into a FEL is more sophisticated; also outcoupling is more complicated; finally, the resonator detuning control claims some special solutions. The waveguide dispersion relation differs from one in the free space. It shifts up the wavelength of the FEL, changes the optimal detuning, and creates a parasitic mode near the critical wavelength of the waveguide. These problems and possible solutions to them are considered., Proceedings of the 37th International Free Electron Laser Conference, FEL2015, Daejeon, Republic of Korea

Published
2015
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90. Electron Bunch Length Measurement using an RF Deflecting Cavity

Author

Park, Sunjeong, Bae, Sangyoon, Jang, Kyu Ha, Jeong, Young Uk, Kim, Eun-San, Kim, Hyun Woo, Mun, Jungho, and Vinokurov, Nikolay

Subjects
Physics::Accelerator Physics, Accelerator Physics, Electron Beam Dynamics
Abstract

Recently, the RF photogun based-ultrafast electron diffraction (UED) system has been developed in KAERI. In the system, the emitted electron bunches are experimentally confirmed to be accelerated up to 3 MeV at 5MW of RF power. And the time duration of the each bunch is initially designed to be less than 50 fs at the sample position. To analyses the performance of the system and to measure exactly the length of the electron bunches, we developed a rectangular type of S-band deflecting cavity working on TM120 mode. The principle of electron deflecting in the cavity, design & mechanical fabrication process and test results will be present in the conference., Proceedings of the 37th International Free Electron Laser Conference, FEL2015, Daejeon, Republic of Korea

Published
2015
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91. Surface-enhanced spectroscopy: Toward practical analysis probe.

Author

Mun, Jungho, Lee, Dasol, So, Sunae, Badloe, Trevon, and Rho, Junsuk

Subjects
*SPECTRUM analysis, *RAMAN scattering, *ELECTROMAGNETIC fields, *SURFACE interactions, *PHYSICS, *INFRARED absorption
Abstract

Surface-enhanced spectroscopy (SES) is a consequence of extreme electromagnetic fields and chemical interactions near a surface. SES is highly sensitive and selective and has been exploited in chemistry, physics, biology, and medicine. It is a rapidly developing technique and is expected to become an important analysis tool. This review introduces theories and concepts of SES techniques including surface-enhanced (SE) Raman scattering, SE infrared absorption, SE chiroptical spectroscopy, and SE fluorescence. Then recent research and applications are discussed to indicate current challenges and future directions. [ABSTRACT FROM AUTHOR]

Published
2019
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