Department News

Professor Seung-Woo Kim’s group develops nonlinear susceptibility extraction method based on high harmonic generation

관리자 2019.08.08

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In the Precision Engineering & Metrology Laboratory (Advisor: Prof. Seung-Woo Kim), Dr. Seunghwoi Han and Dr. Hyunwoong Kim have succeeded in measuring the nonlinear susceptibility of solid materials based on the process of high harmonic generation.
 
Nonlinear susceptibility is the key phenomenon to the development of ultrafast lightwave-driven optoelectronic devices that enable petahertz scale signal manipulation. Previous relevant studies measured only the third-order nonlinear susceptibility by comparing the difference between the nonlinear response that occurs when a strong electric field passes through the medium and the linear response that occurs when a relatively weak electric field passes through it. In this study, they measured the 7th, 9th, and 11th nonlinear susceptibilities of sapphire crystal using the high nonlinearity of high harmonic generation. The measured susceptibilities turned out to exhibit a periodicity depending on the band structure which changes according to the crystal orientation of the material. The research was conducted in collaboration with Professor Seungchul Kim of Pusan ​​National University and Alexandra Landsman of the Max-Planck Institute for Physics of Complex Systems in Germany. The results can be applied to the development of multi-channel signal processing technology, controlled by laser polarization.
 
This research was supported by the National Research Foundation of the Republic of Korea. The results of this study were published on July 22, 2019 under the heading "Extraction of higher-order nonlinear electronic response in solids using high harmonic generation" in the international journal Nature Communications (IF: 11.880).