High-Q Metallic Fano Metamaterials using Subwavelength Slits
파장보다 작은 슬릿을 이용한 높은 Q인자 금속성 Fano 메타물질 연구

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dc.description학위논문 (박사)-- 서울대학교 대학원 : 자연과학대학 물리·천문학부(물리학전공), 2018. 8. 박건식.-
dc.description.abstractIn this thesis, a high-quality-factor (high-Q) metallic Fano metamaterial, in which subwavelength metallic slits are arranged to form asymmetric unit cells, is demonstrated both experimentally and theoretically. First, the previous works on the optical properties of the subwavelength slits are studied in detail in order to understand the physics behind the Fano resonances existing in this structure. Based on the knowledge, Q of the Fano resonances is deliberately tailored in order to maximize it, which is is measured to be unprecedented at 700 at electronics regime, such as microwave and terahertz. The interplay between an extremely low group velocity from the infinite transverse permittivity of the anisotropic metamaterial and the subradiant damping from a Fano-type slit mode is shown to be responsible for the high-Q value. Moreover, the effect of the unwanted geometric parameters such as structural disorder and surface roughness are experimentally studied for the maximization.

As a next step, the feasibility of this metamaterial for a Cerenkov lasing application is numerically investigated. As the moving electron beam interacts with the waveguide modes of the metallic metamaterial, dipole-like modes are induced at each slit aperture, leading to the formation of the Cerenkov wake, the phase velocity of which is adjusted to match that of the electron beam. The optimum Q for optimum output RF coupling can be obtained by controlling the radiation damping or Rayleigh scattering of the trapped Cerenkov light based on structural asymmetries. The resulting improvement in the Cerenkov lasing efficiency is estimated to be more than two orders of magnitude using a particle-in-cell simulation. The proposed high-Q metallic Fano metamaterial that realizes highly efficient CL without mirrors is a strong candidate for several practical applications, especially in very-high-frequency electronic devices such as terahertz.
dc.description.tableofcontentsChapter 1. Introduction 1

1.1. Fano resonance and its applications 1

1.2. Motivation and Goal 4

Bibliography 7

Chapter 2. Literature review: Optical modes in subwavelength slits 9

2.1. Introduction 9

2.2. A finite number of subwavelength slits 10

2.3. An infinite number of subwavelength slits 15

2.4. A doubly periodic array of subwavelength slits (Metallic Fano metamaterials) 21

Bibliography 25

Chapter 3. High-Q Metallic Fano metamaterials using subwavelength slits 27

3.1. Introduction 27

3.2. Design of the metallic metamaterial for the high-Q Fano resonance 28

3.3. The experimental setup and sample preparation at microwave frequency 41

3.4. Measurement of the quality factor of the strongly trapped modes 46

3.5. The effect of the structural asymmetry on radiative damping 51

3.6. The metallic Fano metamaterial at terahertz and optical frequencies 64

Bibliography 66

Chapter 4. Efficient Cerenkov lasing as an application of Fano-enhanced active devices 69

4.1. Introduction 69

4.2. Smith-Purcell and Cerenkov effects in the metallic metamaterial 74

4.3. Fano-enhanced Cerenkov effect 76

4.4. The experimental Scheme of the Fano-enhanced Cerenkov lasing at terhertz frequency 86

Bibliography 90

Chapter 5. Summary and Conclusion 93

Appendix 95

List of publications 119

Conferences 121

요약(국문초록) 123
dc.publisher서울대학교 대학원-
dc.titleHigh-Q Metallic Fano Metamaterials using Subwavelength Slits-
dc.title.alternative파장보다 작은 슬릿을 이용한 높은 Q인자 금속성 Fano 메타물질 연구-
dc.contributor.AlternativeAuthorSeontae Kim-
dc.contributor.affiliation자연과학대학 물리·천문학부(물리학전공)-
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College of Natural Sciences (자연과학대학)Dept. of Physics and Astronomy (물리·천문학부)Physics (물리학전공)Theses (Ph.D. / Sc.D._물리학전공)
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