Biography
Prof. YoungPak Lee
Prof. YoungPak Lee
Hanyang University, Republic of Korea
Title: Electromagnetic Metamaterial Perfect Absorbers and Hyper-transmitter, based on Super-lens
Abstract: 
Super-lensing and perfect absorption of electromagnetic (EM) microwaves using metamaterials (MMs) have been studied vigorously recently for the possible applications in EM-wave cautery, hyper-transmitter, super-lens, EM compatibility, solar energy, bolometer, sensor, etc. Perfect absorption of EM microwaves using MMs is a flourishing research field in expecting the potential applications as above. By minimizing the reflectance and eliminating the transmittance, the design and the fabrication of perfect absorbers (PAs) could be realized in various frequency bands, including the GHz and the MHz bands. The problem of EM noise comes to be more serious according to the advent of ubiquitous society. Extended dissemination of high-speed and high-f digital products and smart equipments has made special EM-wave materials used in various fields. We are investigating advanced meta-structures/materials and MMs for EM-wave absorption, MM technology for EM-wave absorption over 99% and ultrawide-band absorption, and MMs for EM-wave absorption independent of incident angle and polarization.

Especially, an efficient resolution for ultrathin MM PA is proposed and demonstrated in the VHF radio band (30–300 MHz). By adjusting the lumped capacitors and the through vertical interconnects, the absorber is miniaturized to be only λ/816 and λ/84 for its thickness and periodicity with respect to the operating wavelength (at 102 MHz), respectively. Additionally, we utilized the advantages of the initial single-band structure to realize a nearly perfect dual-band absorber in the same range. The results were confirmed by both simulation and experiment at oblique incidence angles up to 50°. Our work is expected to contribute to the actualization of future MM-based devices working at radio frequency. It is also experimentally proven that wide-band good MM absorber for EM wave in 8–18 GHz can be manufactured by water-droplet patterning, in other words, with a very ordinary material. Using a planar and flexible MM, we also obtained the low-frequency perfect absorption even with very small unit-cell size in snake-shape structure.

We have realized the tunable MM hyper-transmitter in the microwave range utilizing simple planar meta-structure. The single-layer MM hyper-transmitter shows that the transmission peak appears at 14 GHz. In case of the dual-layer one, it is possible to control the transmission peak from 5 to 10 GHz. Moreover, all the transmission peaks present transmission over 100%. The reason for being over 100% is also understood. The investigated hyper-transmitter can be used in enhancing the operating distance of the EM wave in many kinds of practical applications. This work was supported by the ICT R&D program of MSIP/IITP, Korea (13-911-01-101).
Biography: 
YoungPak Lee received his B. S. degree from Seoul National University, Korea, in 1975, and the Ph. D. degree in experimental condensed-matter physics in 1987 from Iowa State University, U. S. A. His research involved study on magneto-optical, magnetic, optical and transport properties, and electronic structures of thin films and nanostructures, characterization of the surfaces and interfaces of thin films including multilayers, vacuum science, and so forth since his Ph. D. degree. After many careers in U. S. A., Japan, Germany and Korea, he is now former President of the Korean Physical Society, former President of the Korean Federation of Basic-science, Distinguished Professor, Physics Department of Hanyang University, and Director of Quantum Photonic Science Research Center, Seoul, Korea, which exploited the convergence research of magnetism and optical science. Prof. Lee is also Member of Korea Academy of Science and Technology, Council of Association of Asia-Pacific Physical Societies, Honorary Member of National Academy of Sciences of Ukraine, Distinguished Visiting Professor of Aix-Marseille Univ. (France) and Edith Cowan Univ. (Australia), Guest Distinguished Professor / Professor of 7 Chinese Universities and Institutes, Scientific Advisor of Scientific Council of Materials Science of Vietnamese Academy of Science and Technology. His current investigations include metamaterials and spin-photonic crystals, nanoscopic investigation of morphology and magnetic domain, and magnetic semiconductors based on oxides. He has published 640 SCI papers (the total published number of papers : 750 papers) as of December 2014. Because of these achievements, he has received many kinds of awards (48 awards as of December 2014), including the highest-level Award from the Korean Physical Society (2014), Award by the Korean Minister of Education, Science and Technology (2009), Award by the Korean Minister of Science and Technology (1992), and various academic-paper awards and academic-achievement awards. Based on these recognitions, he was also selected as one of the 'Korean Scientists for the 21st Century' by a main national broadcasting company in 2007. He has led the globalization of Korean physics, based on the leadership in the research on quantum photonic science. So far, he has established the global collaboration network with 42 organizations in 15 countries, including the U. S. A. and China.