유연한 중심구조를 이용한 이온성 전기 광학 결정
Ionic Electro-optic Crystals Based on Flexible Structures
- 주제(키워드) Organic nonlinear optic , Stilbazolium derivatives , flexible core structures , ionic electro-optic crystal
- 발행기관 아주대학교
- 지도교수 권오필
- 발행년도 2010
- 학위수여년월 2010. 8
- 학위명 석사
- 학과 및 전공 일반대학원 분자과학기술학과
- 실제URI http://www.dcollection.net/handler/ajou/000000010848
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Organic nonlinear optical crystals have attracted much interest due to their numerous design possibilities and larger and faster optical nonlinaerities when compared to inorganic crystals. Among these materials, the bench-mark stilbazolium crystal, DAST (N,N-dimethylamino-N’-methylstilbazolium p-toluenesulfonate) is the most investigated one and also the one presenting the highest electro-optical and nonlinear optical figures of merit among the presently available bulk organic crystals. However, salt-typed stilbazolium chromophores are dissolved in water and formed centrosymmeteric hydrated phase, which occur a damage by humidity and limit to apply various crystal growth techniques. In this paper, new cation core structures based on N-benzyl pyridinium salt with various substituents ( X : -H for BP1, -CH3 for BP2, -(CH3)2 for BP3 ) on the benzyl group have been investigated for noncentrosymmetric molecular ordering in the crystalline state. In BP3 chromophore, two methyl groups on the benzyl ring can be given more asymmetry of the chromophore shape. Among three N-benzyl pyridinium cations with p-toluenesulfonate anion, BP3 crystals exhibit acentric crystal structure (monoclinic, P21 phase) with a large macroscopic optical nonlinearity of 540 times second harmonic generation efficiency as that of urea at non-resonant frequency 1.9 μm. By introducing non-polar benzyl group, the BP3 chromophores have not formed hydrated phase crystals with water in contrast to DAST crystals. Moreover, the one-order lower solubility in water of BP3 than that of DAST causes good humidity resistance and it can be applied to various crystal growth techniques. We demonstrate THz generation with as-grown BP3 crystals without any complicated polishing and cutting procedures by optical rectification using 180 fs pulses at pump wavelength of 836 nm.
more목차
I. Introduction
II. Brief Review
II.1 Nonlinear Optical Effects
II.1.1 Nonlinear Optical Responses
II.1.2 Second-Harmonic Generation (SHG)
II.1.3 Electro-Optic Effect
II.2 Organic Nonlinear Optical Materials
II.2.1 Comparison of Organic and Inorganic Materials for Nonlinear and
Electro-Optics
II.2.2 Organic Molecules for Second-Order Nonlinear Optics
II.2.3 Relation between Microscopic and Macroscopic Nonlinearities
II.2.4 Microscopic Design of Molecular Structure
II.3 Organic Nonlinear Optical Single Crystals
II.3.1 Approaches for Noncentrosymmetric Crystalline Packing
II.3.1.1 Use of Strong Coulomb Interactions: DAST
II.3.2 Crystal Growth of Organic Materials
II.3.3 Bulk Single Crystals for THz Wave Applications
II.3.4 Challenges of Organic Nonlinear Optical Crystals
III. Experiments
III.1 Chemical Structures
III.2 Synthesis
III.2.1 Materials
III.2.2 General Characterization
III.2.3 Synthesis of BPnCl-
III.2.4 Synthesis of BPn Chromophore
III.3 Powder SHG Measurements
III. 4 Crystal Structure Data for the BP3 Crystal
IV. Results and Discussions
IV.1 Design of New Core Structure for Acentric Molecular Ordering
IV.2 Characterization and Powder Nonlinear Optical Studies
IV.3 Single Crystal Structure
IV.4 Environmental Stability and Bulk Crystal Growth
IV.5 THz Generation
V. Conclusions
VI. References
