Development of Organic Nonlinear Optical Crystals and Crystal Engineering Techniques for THz Photonics
Development of Organic Nonlinear Optical Crystals and Crystal Engineering Techniques for THz Photonics
- 주제(키워드) organic crystals , nonlinear optics , terahertz waves , crystal engineering techniques , intermolecular interactions
- 발행기관 아주대학교
- 지도교수 권오필
- 발행년도 2017
- 학위수여년월 2017. 8
- 학위명 박사
- 학과 및 전공 일반대학원 분자과학기술학과
- 실제URI http://www.dcollection.net/handler/ajou/000000025553
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
In this thesis, I describe several studies based on organic nonlinear optical crystals for highly efficient THz photonics. In order to help the better understanding for the THz photonics utilizing organic single crystals, the several explanations, including definition, application and generation/ detection method of THz wave are presented. In addition, conventional requirements for nonlinear optical molecular structures and several examples of crystal engineering technics for non-centrosymmetric crystal packing with high nonlinear optical response and THz wave generation are also denoted. We have investigated the new ionic organic π-conjugated crystals with various anion for highly efficient THz wave generation. Moreover, we have developed various crystal engineering techniques utilizing different solvents, additives, tailor-made auxiliaries and substrates to achieve highly favorable material properties and improved optical performances including THz wave generation. Using a strong benzothiazolium electron-acceptor group, we have successfully investigated new HMB (2-(4-hydroxy-3-methoxystyryl)-3-methylbenzo[d]thiazol-3-ium) crystals showing large macroscopic optical nonlinearity and excellent crystal characteristic for THz wave generation, which lead to very intense and broadband THz wave generation efficiency (one order of magnitude higher than standard inorganic ZnTe crystal) by optical rectification (OR). We have demonstrated the growth of organic ionic nonlinear optical crystals with large area and suitable thickness for highly efficient THz generation, in which nucleation is induced by local supersaturation on a template and crystals grow following the surface of the template based on strong hydrogen bonds. We have developed the new morphological crystal engineering technique introducing in-situ tailor made additives for organic phenolic nonlinear optical crystals. The morphology of phenolic crystals grown with in situ tailor-made additives are changed to be more optimal for photonic applications, which allows the two optical configuration within a one single crystal towards THz photonics. We have observed favorable crystal growth characteristics including large area and desired thickness, optimal for THz wave photonics, by new crystal engineering technique using confinement geometry. By resulting crystal, the correlation between optical-to-THz conversion characteristics and crystal characteristics are successfully investigated, where grown crystal exhibits higher THz amplitudes compared to crystals grown by typical solution growth method. We have examined the origin of solubility behavior of polar π-conjugated crystals in mixed solvent system of polar non-aromatic and non-polar aromatic solvents are experimentally provided. The aromatic characteristics of solvents lead to the variation of crystal characteristics including morphology and polymorphism of single crystals.
more목차
CHAPTER 1 1
Introduction 2
CHAPTER 2 THz Technology and Molecular Design and Crystal Engineering Techniques for Organic Nonlinear Optical Crystals 6
2.1 Terahertz (THz) Technology 7
2.2 THz Generation and Detection 9
2.2.1 Optical Rectification (OR) 9
2.2.2 Electro-Optic Sampling (EOS) 12
2.3 Organic Nonlinear Optical Crystal for THz Photonics 15
2.3.1 Design of Nonlinear Optical Molecules 15
2.3.2 Non-centrosymmetric Crystal Packing 17
2.3.3 Relationship between Optical Nonlinearity and Crystal Packing 18
2.4 Example of Organic Electro-Optic Crystals 21
2.4.1 Pyridinium-Based Crystals 21
2.4.2 Configurationally Locked Polyene (CLP)-Based Crystals 24
2.4.3 Quinolinium-Based Crystals 26
2.5 Crystallization of Polar Organic π-conjugated Crystals 31
2.6 Crystal Engineering (Growth) Techniques 32
2.6.1 Crystal growth in Different Solvents 32
2.6.2 Crystal Growth with Additives 37
2.6.3 Crystal Growth with Tailor-Made Auxiliaries 43
2.6.4 Crystal Growth on Substrates with Surface Interactions 44
2.7 Concluding Remarks 48
CHAPTER 3 Benzothiazolium Single Crystals: A New Class of Nonlinear Optical Crystals with Efficient THz Wave Generation 49
3.1 Introduction 50
3.2 Results and Discussion 51
3.2.1. Molecular Design with Strongly Electronegative Group 51
3.2.2. Single Crystal Structure 55
3.2.3. Microscopic and Macroscopic Optical Nonlinearity 57
3.2.4. Large Crystal Growth and Characteristics 61
3.2.5. THz Generation 64
3.3 Conclusion 70
3.4 Experimental Section 71
CHAPTER 4 Organic Ionic Electro-Optic Crystals Grown by Specific Interactions on Templates for THz Wave Photonics 77
4.1 Introduction 78
4.2 Results and Discussion 79
4.2.1. Design of Crystal Engineering: Materials, Requirements and Experimental Condition 79
4.2.2. Crystal Growth Process with Different Concentration 81
4.2.3. The Mechanisms of Nucleation and Crystal Growth 84
4.2.4. THz Generation with As-Grown Crystals on Template 88
4.3 Conclusion 90
4.4 Experimental Section 90
CHAPTER 5 In Situ Tailor-Made Additives for Molecular Crystals: A Simple Route to Morphological Crystal Engineering 92
5.1 Introduction 93
5.2 Results and Discussion 94
5.2.1. Design of Crystal Engineering: Materials and Sample Preparations 94
5.2.2. Crystal Growth with In Situ/ Conventional Tailor-Made Additives 96
5.2.3. Demonstration of Intermolecular Interactions 102
5.2.4. THz Generation with Crystals Grown by In Situ Tailor-Made Additive 108
5.3 Conclusion 111
5.4 Experimental Section 111
CHAPTER 6 Electro-Optic Crystals Grown in Confined Geometry with Optimal Crystal Characteristics for THz Photonic Applications 115
6.1 Introduction 116
6.2 Results and Discussion 118
6.2.1. Crystal Engineering for THz Applications: Requirements and Our Approach 118
6.2.2. Optimal Thickness for THz-Wave Generation 122
6.2.3. Large-Area Thickness-Controlled Crystal Growth Experiments 124
6.2.4. THz Generation with Crystals As-Grown in Confined Geometry 131
6.3 Conclusion 133
6.4 Experimental Section 133
CHAPTER 7 Origin of Solubility Behavior of Polar π-Conjugated Crystals in Mixed Solvent Systems 135
7.1 Introduction 136
7.2 Results and Discussion 138
7.2.1. Solubility in Mixed Solvents 138
7.2.2. π-π Interactions with Aromatic Solvents 145
7.2.3. Crystal Growth with Aromatic Solvents 149
7.3 Conclusion 155
7.4 Experimental Section 155
CHAPTER 8 Concluding Remarks 160
References 164
Chapter 1 165
Chapter 2 172
Chapter 3 188
Chapter 4 195
Chapter 5 199
Chapter 6 205
Chapter 7 212
