Numerical Analysis and Designs of Terahertz Photomixer and Photoconductive Antennas
테라헤르츠 (terahertz) 대역에서 동작하는 광 혼합기 (photomixer) 와 광전도 안테나 (photoconductive antenna) 에 대한 수치 해석 및 설계
- 발행기관 아주대학교
- 지도교수 Park Ikmo (박익모)
- 발행년도 2013
- 학위수여년월 2013. 2
- 학위명 박사
- 학과 및 전공 일반대학원 전자공학과
- 실제URI http://www.dcollection.net/handler/ajou/000000013489
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Terahertz (THz) science and technology have made significant progress in the past decades. However, the use of THz waves was not fully realized due to the absence of practically suitable and efficient signal sources. The THz radiation can be generated by using short laser pulses or using an optical beat for the pump of the photoconductive antenna. The physical mechanism of the former technique can be divided into two groups, ultrafast surge effects and nonlinear optical effects. The latter technique was preferred to as photomixing or optical heterodyne. A common method to detect THz radiation is through Electro-Optic Sampling (EOS) measurement to determine the THz electric field. In both THz pulsed and CW photomixing systems the antenna is one of the most important elements to couple radiation into or collect radiation from free space. However, an efficient antenna design for THz applications has been a difficult subject of huge interest. The effort on new kinds of integrated antennas with new devices in order to increase the power and the efficiency of the radiated structured is the main goals of our work. In this work, we numerically studied and investigated the characteristics of several antenna types for both THz pulsed and CW photomixing systems. We proposed some antenna design which obtaining high total efficiencies to partly solve the low output problem. Besides, the issue of improved antenna directivity was also particular considered in this work. This work was completed with a special topics of photoconductive antenna used in a THz pulsed system. The results that we obtained contribute in providing a more throughout understanding about the important role of antenna in the radiation of the THz waves.
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ABSTRACT i
TABLE OF CONTENTS ii
LIST OF FIGURES iii
LIST OF TABLES iv
I. INTRODUCTION 1
1.1 Terahertz radiation and sources 1
1.2 Terahertz photoconductive antenna 2
1.3 Terahertz photomixer antenna 4
1.4 Substrate for terahertz antenna design 8
1.5 Thesis organization 9
1.6 References 10
II. TERAHERTZ RESONANT ANTENNAS ON SEMI-INFINITE AND LENS SUBSTRATE 13
2.1 Introduction 13
2.2 Antennas and substrate geometries 16
2.3 Antenna characteristics 18
2.3.1 On semi-infinite substrate 18
2.3.2 On extended hemispherical Si lens substrate 21
2.4 Summary 27
2.5 References 30
III. TERAHERTZ SELF-COMPLEMENTARY ANTENNAS ON LENS SUBSTRATE 33
3.1 Introduction 33
3.2 Antenna geometries for comparison 36
3.3 Antenna characteristics in a broadband THz frequency 38
3.4 Summary 46
3.5 References 47
IV. ANTENNA ON A GaAs MEMBRANE STRUCTURE FOR HIGH TOTAL EFFICIENCY 49
4.1 Introduction 49
4.2 Antennas and membrane configurations 51
4.3 Antenna characteristics 53
4.3.1 Geometry effects of the GaAs membrane substrate on the antenna performance 53
4.3.2 Effects of the bias line structure on the antenna performance… 60
4.4 Summary 64
4.5 References 65
V. ANTENNA ON A HYBRID GaAs MEMBRANE AND SI LENS SUBSTRATE FOR A TERAHERTZ PHOTOMIXER 67
5.1 Introduction 67
5.2 Antennas configurations 70
5.3 Antenna characteristics with a modified PBG bias line 73
5.4 Photomixer antenna characteristics with a non-contact lens substrate 78
5.5 Summary 85
5.6 References 86
VI. ANTENNA ON A GaAs MEMBRANE COVERED BY A FREQUENCY-SELECTIVE SURFACE FOR A TERAHERTZ PHOTOMIXER 88
6.1 Introduction 88
6.2 Description and modeling of the structure 91
6.3 THz photomixer and antenna characteristics 93
6.3.1 Effect of the size of cavity in a GaAs substrate 94
6.3.2 Effect of the number of holes in a array 97
6.3.3 Effect of the quartz substrate supporting the hole array 99
6.4 Final design and simulated results 102
6.5 Summary 102
6.6 References 103
VII. INVESTIGATION OF ANTENNA DESIGN PARAMETER EFFECTS ON A TERAHERTZ PHOTOCONDUCTIVE DIPOLE ANTENNA 106
7.1 Introduction 106
7.2 Antenna design 108
7.3 Antenna characteristics 109
7.3.1 Bias line length effect 109
7.3.2 Center dipole length effect 117
7.4 Summary 119
7.5 References 120
VIII. IMPACT OF VARYING DC BIAS STRIPLINE CONNECTION ANGLE ON TERAHERTZ PHOTOCONDUCTIVE DIPOLE ANTENNA CHARACTERISTICS 123
8.1 Introduction 123
8.2 Antenna geometry 125
8.3 Antenna characteristics 126
8.4 Summary 137
8.5 References 138
IX. CONCLUSIONS AND FUTURE WORKS 141
9.1 Summary and key contributions 141
9.2 Future works 143
AUTHOR’S PUBLICATIONS 145
