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A study on the optical device design based on coupled mode theory
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | 김상인 | - |
| dc.contributor.author | 허형준 | - |
| dc.date.accessioned | 2019-08-13T16:41:16Z | - |
| dc.date.available | 2019-08-13T16:41:16Z | - |
| dc.date.issued | 2019--8 | - |
| dc.identifier.other | 29317 | - |
| dc.identifier.uri | https://dspace.ajou.ac.kr/handle/2018.oak/15569 | - |
| dc.description | 학위논문(박사)--아주대학교 일반대학원 :전자공학과,2019. 8 | - |
| dc.description.tableofcontents | Table of Contents Page Acknowledgement Abstract i List of Figures iv Chapter 1: Introduction 1 1.1 Optical devices and coupling of modes 1 1.2 Overall objectives 2 1.3 Thesis outline 2 Reference 4 Chapter 2: Theoretical background of mode coupling 5 2.1 The optical modes 5 2.1.1 guided modes 5 2.1.2 resonant modes 7 2.2 Dielectric perturbation theory 8 2.3 Two parallel guided modes coupling 11 2.3.1 Co-directional coupling 12 2.3.2 Contra-directional coupling 14 2.4 Single resonant mode coupling 16 2.4.1 One port modeling 16 2.4.1 Two port modeling 18 Reference 20 Chapter 3: Broadband absorption enhancement of monolayer graphene by prism coupling in visible light 21 3.1 Introduction 21 3.2 Broadband absorption structure 22 3.2.1 Transfer matrix method 23 3.2.2 Modeling by temporal coupled mode theory 25 3.2.3 Critical coupling for perfect absorption 27 3.3 Fabrication process 32 3.3.1 PECVD process for silica deposition 34 3.3.2 Graphene wet transfer 37 3.4 Measurement setup 38 3.4.1. Configurations of measurement setup 38 3.4.2. Considerations 39 3.5 Sample characteristics 41 3.6 Absorption measurement results 45 3.7 Summery 49 Reference 50 Chapter 4: Design of graphene-based integrated wavelength selective photodetectors 53 4.1 Introduction 53 4.2 Structure of wavelength selective photodetector 54 4.2.1 Modal analysis 56 4.2.2 Phase matching condition 61 4.2.3 The coupled mode theory modeling 62 4.3 Design of structural parameters 63 4.4 Wavelength selective absorption 67 4.5 Absorption for multilayer graphene 70 4.6 Summery 71 Reference 73 Chapter 5: Tailoring Fano resonance for flat-top broadband reflectors based on single guided-mode resonance 76 5.1 Introduction 76 5.2 Tailoring Fano resonance polarity 77 5.3 Temporal coupled mode theory modeling 79 5.3.1 The even mode resonant reflector 82 5.3.2 The odd mode resonant reflector 85 5.3.3 The fractional bandwidth according to decay rate 87 5.4 High contrast grating structure 88 5.5 Summery 92 Reference 93 Chapter 6: Conclusion and Future works 95 Authors Publications 97 | - |
| dc.language.iso | eng | - |
| dc.publisher | The Graduate School, Ajou University | - |
| dc.rights | 아주대학교 논문은 저작권에 의해 보호받습니다. | - |
| dc.title | A study on the optical device design based on coupled mode theory | - |
| dc.type | Thesis | - |
| dc.contributor.affiliation | 아주대학교 일반대학원 | - |
| dc.contributor.department | 일반대학원 전자공학과 | - |
| dc.date.awarded | 2019. 8 | - |
| dc.description.degree | Doctoral | - |
| dc.identifier.localId | 951942 | - |
| dc.identifier.uci | I804:41038-000000029317 | - |
| dc.identifier.url | http://dcoll.ajou.ac.kr:9080/dcollection/common/orgView/000000029317 | - |
| dc.description.alternativeAbstract | Coupled-mode theory (CMT) can be modeled by properties of uncoupled resonant and/or guided mode without any complicated mathematical derivations. This provides for an intuitive grasp and a physical insight into the structural parameters for the efficient design and analysis of optical devices. The coupling between two waveguides is modeled through the formalism of a coupling-in-space and a resonant mode coupling with one or more ports in coupling-in-time. Rigorous mathematical derivations of CMT based on perturbation theory provide an accurate prospect of coupling properties. In this thesis, the author designed various optical devices, which had a high performance, using coupled mode theory. In the model of the directional coupling of a resonant mode with two ports, the broadband absorption enhancement of a monolayer graphene embedded in the center of a cavity was experimentally demonstrated by using prism coupling to meet the critical coupling conditions. The experimental results were comparable to theoretical calculations in the visible range. A compact opto-electronic coupler between the side-polished fiber and the silicon waveguide was used to enhance the graphene. It had a wavelength selectivity and a low insertion loss that were suitable for a course wavelength division multiplexer (CWDM) photodetector and was modeled as a contra-directional coupler through periodic gratings. The ultra-wideband reflector was designed by using a new approach that tailors Fano resonance between the single guided mode resonance (GMR) mode and the Fabry-Perot resonance (FPR) background mode in the high contrast grating structure (HCGs). Analysis of the new method was based on a coupled mode theory for designing reflectors provided a more intuitive understanding of the device properties in comparison to previous methods. Most of the previous investigations were conducted through modal analysis and modeling of coupled mode theory; and were verified through various numerical methods such as the transfer matrix method (TMM), the finite element method (FEM), and the rigorous coupled wave analysis (RCWA). The TMM calculated the absorption and reflectance of monolayer graphene through prism coupling into the dielectric mode. The FEM simulated the transmittance and absorption of two guided mode couplers and modal analysis. RCWA simulated the reflectance and transmittance of a wideband reflector using HCGs. | - |
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