마이크로공정과 전자빔 기반의 테라헤르츠 증폭/발진기 개발 THz sources based on vacuum electron devices are promising for its high power performance with a compact system. In our team, we develop ~300 GHz folded waveguide traveling tube amplifiers, ~100-300 GHz gyrotron oscillators, and high power amplifiers with solid state driver: I. Lee et al., “Microscopic analyses of electrical conductivity of micromachined-folded waveguides based on surface roughness measurement for terahertz vacuum electron devices,” IEEE Trans. on Terahertz Science and Technology, vol.8, iss.6 (2018) I. Lee et al., “Self-driving, energy-recirculating micromachined G-band folded waveguide traveling-wave tube,” IEEE Trans. Electron Devices, vol.65, iss.8 (2018) A. Sawant et al., “Development of the full package of gyrotron simulation code,” Jour. of Korean Phys. Soc. (2018) 과제지원: 국방과학연구소, 한국연구재단 핵융합기초연구, 핵융합연구소

6G E-band 대역 OAM-MIMO 무선 통신 시스템 연구 We develop multi-electron beam based E-band TWT for 6G OAM MIMO wireless communication system. A. Sawant et al., “Orbital angular momentum (OAM) of rotating modes driven by electrons in electron cyclotron masers,” Scientific Reports 7, 3372 (2017) 과제지원: 삼성미래기술육성사업

테라헤르츠 전자기파 전송 및 모드변환 Security communication link is a very attractive application by using high power millimeter/THz wave beams. Our team can design and build extremely higher order rotating modes (HOM) or whispering gallery mode (WGM) by using in-house EM code. Current work focuses on generating HOM or WGM and using them as free-space communications. Related publications: I. Lee et al., “Accurate identification of whispering gallery mode patterns of gyrotron with stabilized electro-optic imaging system,” Phys. Plasm 25, 013116 (2018) A. Sawant et al., “Generation and validation of topological charges of high-power gyrotron orbital angular momentum beams from phase retrieval algorithm,”IEEE Trans. Terahertz Sci. Tech., vol.7, iss.2(2017) 과제지원: 국방과학연구소, 한국연구재단 개인연구사업, 핵융합기초연구

RF/밀리미터파/THz 대역 물질 특성 연구 Precise measurement of electromagnetic wave fields is very critical characterizing an antenna performance as well as characterizing material properties. We are developing precise dielectric properties measurement technique in the range of tens of GHz to hundreds of GHz. Related publications: H. E. Choi et al., “Error tolerant method of dielectric constant measurement using a selective resonance mode at W-band,” IEEE Trans. Microwave Theory and Tech. (2019) M. S. Choe et al., “Measuring the carrier lifetime by using a quasi-optical millimeter- and THz-wave system,” Appl. Phys. Lett. 110, 074101 (2017) I. Lee et al., “In-situ endoscopic observation of higher-order mode conversion in a microwave mode converter based on an electro-optic probe system,” Opt. Exp. 22 (2014) K. H. Kim et al., “Near field pattern of large aperture higher order mode generator using back propagated fields in free space,” IEEE Trans. Plas. Sci. 42 (2014) 과제지원: 한국연구재단 중견연구사업, 핵융합기초연구

고출력 전자기파를 이용한 위험물 탐지 기법 연구 Plasma breakdown by Millimeter-wave/THz sources has been a long time research topic in the plasma community. We are interested in possible detection of standoff radioactive material using a highly focused THz beam. Related publications: D. S. Kim et al., “Remote detection of radioactive material using high-power pulased electromagnetic radiation,” Nat. Comm. 8, 15394 (2017) D. S. Kim et al., “Study on statistical breakdown delay time in Argon gas using a W-band millimeter-wave gyrotron,” Phys. Plasm, 23, 043505 (2016) D. S. Kim et al., “Numerical estimation on free electrons generated by shielded radioactive materials under various gaseous environments,” AIP Advances 3, 062109 (2013) 과제지원: 한국연구재단 개인기본연구사업, 중견연구사업