Control of Fano Resonance in Plasmonic and Optical Systems for Highly-Sensitive Spectral Responses : 플라즈모닉 및 광학 시스템에서의 스펙트럼 민감도 향상을 위한 파노 공명의 제어

다국어 초록 (Multilingual Abstract)

The concept of Fano resonance from quantum physics has originally been applied to describe the configuration interaction in the rare gas excitation, which is one of the universal phenomena caused by the wave interference. The main feature of Fano resonance is the sharp, asymmetrically shaped spectrum, which is due to the interference between two resonant modes of different life-time. To exploit this intriguing spectral feature, a variety of Fano resonant nanostructures implementing optical analogue of quantum-mechanical Fano resonance have been proposed and studied, including clusters of plasmonic nanoparticles and metamaterial platforms. During my Ph.D study I have been trying to bring the concept of Fano resonance into the field of optical and plasmonic systems to provide some novel paths for the existing applications such as on-chip plasmonic devices and net optical spin excitation. In this dissertation, the characteristics of asymmetrically shaped spectral responses for the Fano resonant structures are investigated in the plasmonic stub-waveguide systems and optical chiral system.
In the theoretical part of this dissertation, the theoretical descriptions about the Fano resonance phenomena are provided in several different formalism, such as the original quantum perturbation analysis, analogy with classical oscillators, and the simple and general coupled mode theory. Based on the coupled mode theory model, I also establish the Fano asymmetry parameter, which is the key physical parameter for the quantification of the Fano resonance phenomenon.
Through the numerical and theoretical studies, we firstly propose a plasmonic sensor based on the control of the degree of Fano asymmetry, with the plasmonic metal-insulator-metal waveguide-stub junction structure. we also introduce an ultra-efficient plasmonic on-chip modulator based on the concept of plasmonic induced transparency. Excellent performance with 12dB transmission contrast at ~60% throughput is achieved due to the extremely sharp spectral profiles, which is caused by the Fano interference using a pair of plasmonic metal-insulator-metal stubs. A novel path for the conservative and nonmagnetic optical spin excitation is introduced utilizing the spin handedness-dependent anti-symmetric Fano resonances, with Hermitian material parameters. Utilizing the pure optical spin excitation density and its extreme spectral sensitivity in the suggested design, ‘optical spin switching’ is also introduced with experimentally accessible material parameters.

목차 (Table of Contents)

• Abstract i
• Contents iv
• List of Figures ix
• Chapter 1 Introduction 1
• 1.1 Motivation 1
• 1.2 Fano Resonance in the Spectral Domain 2
• 1.2.1 Asymmetrically shaped spectrum 2
• 1.2.2 Fano Asymmetry Parameter 3
• 1.3 Fano Resonance in the Spatial Domain 5
• 1.3.1 Introduction of Goos-Hanchen shift 5
• 1.3.2 Giant Goos-Hanchen shift with Fano Resonance 7
• 1.4 Optical Fano Resonance in the Temporal Domain 8
• 1.5 Achievements and Challenges 11
• 1.6 Dissertation Overview 12
• Chapter 2 Theoretical Model for the Fano Resonance 15
• 2.1 Introduction 15
• 2.2 The Original Fano Approach 16
• 2.3 Modeling with Classical Oscillators 19
• 2.4 Modeling with Coupled Mode Theory 23
• 2.4.1 Why Coupled mode formalism 23
• 2.4.2 Basic theory of coupled mode theory 23
• 2.4.3 Coupled mode theory model for the Fano resonance 27
• 2.5 Summary 30
• Chapter 3 Fano Resonance in Plasmonic MIM Waveguide 31
• 3.1 Introduction 32
• 3.2 CMT Analysis of Plasmonic MIM Stub 34
• 3.2.1 CMT Modeling of MIM Stub Structure 34
• 3.2.2 Derivation of Fano Asymmetric Parameter 37
• 3.3 Interpretation of Fano-type Spectral Asymmetry in MIM stub 39
• 3.4 Control of Fano Resonance in MIM stub 41
• 3.4.1 Dependency on the Refractive Index of the Junction 41
• 3.4.2 Dependency on the Stub Length 43
• 3.5 Summary 45
• Chapter 4 Plasmon-Induced Transparency in MIM Stub Pair 46
• 4.1 Introduction 47
• 4.2 Fano Asymmetry in EIT 49
• 4.2.1 Theoretical Background of EIT 49
• 4.2.2 Naturally Asymmetric Spectral Response of EIT 50
• 4.3 Realization and Control of Fano Asymmetry in Plasmon-Induced Transparency 53
• 4.3.1 Plasmon-Induced Transparency 53
• 4.3.2 CMT modeling of Asymmetric PIT in MIM Stub Pair 57
• 4.3.3 Control of Spectral Asymmetry of PIT 59
• 4.4 MIM Plasmonic Modulator 61
• 4.4.1 Schematics of the MIM Modulator 61
• 4.4.2 Optimization of the Structure 63
• 4.5 Summary 66
• Chapter 5 Fano Resonance Induced Optical Spin Excitation 67
• 5.1 Introduction 68
• 5.2 Optical Spin-Angular Momentum and Chiral Material 70
• 5.2.1 Theoretical background of circular birefringence 71
• 5.2.2 Optical SAM Excitation based on Spectral Separation 72
• 5.2.3 Spectral Separation from Antisymmetric Fano Resonances 75
• 5.3 Theoretical Modeling 79
• 5.3.1 CMT Modeling in Temporal Domain 79
• 5.3.2 Derivation of Fano Asymmetry Parameter 83
• 5.4 Optical Spin Switching 86
• 5.5 Summary 90
• Chapter 6 Conclusion 91
• 6.1 Summary 91
• 6.2 Outlook 93
• Journal Publications by the Author 95
• Bibliography 97
• 초 록 111