Adaptive control of EUV high harmonic generation spectrum by modulation of the driving laser pulse구동레이저 변조를 통한 극자외선 고차조화파 생성 스펙트럼 제어

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The generation of extreme ultraviolet (EUV) radiation has been a field of much interest due to the potential applications in spectroscopy, nanoscale imaging and machining. In particular, the nonlinear light-matter interaction process of high harmonic generation (HHG) is known to produce broadband coherent EUV radiation, which may be generated in the form of attosecond pulses with short enough driving laser pulses. Traditionally being generated from gaseous atoms or plasma, the process of HHG has recently been demonstrated in solid state materials as well. Although the process in solids exhibits similarities to atomic HHG, there are some discrepancies which occur from many-body effects and propagation effects. Much research has been carried out to reveal the origin of HHG in solids and probe the internal electron dynamics, nevertheless, attempts to generate various different EUV spectra and applications of the resultant radiation haven’t yet been investigated in depth. In this dissertation, we experimentally produce EUV high harmonics from various solid materials and observe its dependence on the driving laser field strength and waveform. Significant spectral modulations of EUV spectra for sapphire and MgO crystals are observed for varying driving laser intensities. In particular, the 7th harmonic in sapphire and 5th harmonic in MgO exhibit significant deformations for increasing laser field strengths. Waveform dependent behaviour of the EUV spectrum is also investigated with the aid of ultrafast pulse shaping techniques. Adapting the 4f configuration, the driving laser spectrum is separated and pulse shaped by a spatial light modulator. The pulses are finally optimized to enhance and control the EUV spectrum into desired shapes with feedback control loops and genetic algorithms. The results of this research exhibit potentials in arbitrary EUV spectrum generation and applications to EUV spectroscopy and attosecond science.
Advisors
Kim, Seung-Wooresearcher김승우researcher
Description
한국과학기술원 :기계공학과,
Publisher
한국과학기술원
Issue Date
2020
Identifier
325007
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 기계공학과, 2020.8,[iii, 67 p. :]

Keywords

High harmonic generation▼aultrfast pulse shaping▼anonlinear optics▼alight-matter interaction▼aspectral modulation; 고차조화파 생성▼a초고속 펄스 성형▼a비선형 광학▼a빛-물질 상호작용▼a스펙트럼 변조

URI
http://hdl.handle.net/10203/284319
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=924306&flag=dissertation
Appears in Collection
ME-Theses_Ph.D.(박사논문)
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