Electromagnetic coupling of optical dipole antennas
- 주제(키워드) optical antenna , metamaterial , plasmonics
- 발행기관 고려대학교 대학원
- 지도교수 박규환
- 발행년도 2018
- 학위수여년월 2018. 2
- 학위구분 박사
- 학과 대학원 물리학과
- 원문페이지 103 p
- 실제URI http://www.dcollection.net/handler/korea/000000080929
- 본문언어 영어
- 제출원본 000045932633
초록/요약
In this thesis, I investigate the electromagnetic interaction between optical antennas. Due to electromagnetic fields scattered from neighbored antenna, electromagnetic response of coupled antennas changes from that of a single antenna. Double slot antennas are discussed as coupled optical antennas. Double slot antennas have two modes with distinct optical properties. Modes of double slot antennas and interaction between antennas are interpreted through coupled oscillator model. The validity of the oscillator model is demonstrated by microwave experiment, analytic and numerical calculation. Especially, I investigate about dark mode, one mode of double slot antennas. To excite the dark mode under plane wave, phase of electric field is controlled by additional structure. Suggested structure controls ratio between two modes of double slot antennas by polarization state which result in control of radiation pattern. As an example of the application of optical antenna, optical force by slot antenna is discussed. Various manipulations are presented including optical trapping, using enhanced and localized electromagnetic fields. Lastly, periodic optical antenna array can be regarded as metamaterial when period is smaller than the wavelength. And optical properties of the metamaterial are characterized by an effective permittivity and effective permeability. The method of defining optical constants of a material is discussed from reflectance, transmittance, and the Kramers-Kronig relation.
more목차
1. Introduction
2. Electromagnetic interaction between plasmonic resonators
2.1 Electromagnetic fields around double slots 5
2.2 Coupled oscillator model with dynamic coupling coefficient 17
2.3 Normal modes of coupled oscillators and determination of the screening factor 22
2.4 Electromagnetically induced transparency (EIT) in asymmetric oscillators 31
2.5 Conclusion 35
3. Mode selection of coupled resonators by polarization state
3.1 Phase control by polarization state 38
3.2 Selective excitation of the dark and bright mode by polarization state 40
3.3 Radiation pattern control using the dark and bright mode 45
3.4 Microwave experiment with horn antenna 50
3.5 Conclusion 51
4. Optical force generated by slot antenna
4.1 Optical trapping by slot antenna 54
4.2 Manipulating objects using double slot antenna 58
4.3 Conclusion 61
5. Optical constant retrieval based on causality
5.1 Parameter retrieval of free standing slab 63
5.2 Parameter retrieval of a slab in waveguide 73
5.3 Waveguide calculation in FDTD 80
5.4 Conclusion 83
Bibliography
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