Organic Nonlinear Optical Single-Crystalline Thin Film Grown by Physical Vapor Deposition for Terahertz Generation

Uchida, Hirohisa; Yamazaki, Ryo; Oota, Kengo; Okimura, Koutarou; Minami, Tsubasa; Takeya, Kei; Kawase, Kodo

doi:10.1021/acs.cgd.8b00388

Cited by 11 publications

(7 citation statements)

References 32 publications

(57 reference statements)

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“…OH1 has very good crystal processing possibilities from solution, including high optical quality bulk crystals [46,68,71] and large-area single crystalline thin films on substrates [86]. High-quality OH1 thin films can be also grown by the physical vapor deposition [87]. OH1 has been found particularly effective for THz-wave applications [85,[88][89][90][91][92][93][94][95][96][97][98].…”

Section: Non-ionic Organic Nlo Crystalsmentioning

confidence: 99%

Organic Crystals for THz Photonics

et al. 2019

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Organic crystals with second-order optical nonlinearity feature very high and ultra-fast optical nonlinearities and are therefore attractive for various photonics applications. During the last decade, they have been found particularly attractive for terahertz (THz) photonics. This is mainly due to the very intense and ultra-broadband THz-wave generation possible with these crystals. We review recent progress and challenges in the development of organic crystalline materials for THz-wave generation and detection applications. We discuss their structure, intrinsic properties, and advantages compared to inorganic alternatives. The characteristic properties of the most widely employed organic crystals at present, such as DAST, DSTMS, OH1, HMQ-TMS, and BNA are analyzed and compared. We summarize the most important principles for THz-wave generation and detection, as well as organic THz-system configurations based on either difference-frequency generation or optical rectification. In addition, we give state-of-the-art examples of very intense and ultra-broadband THz systems that rely on organic crystals. Finally, we present some recent breakthrough demonstrations in nonlinear THz photonics enabled by very intense organic crystalline THz sources, as well as examples of THz spectroscopy and THz imaging using organic crystals as THz sources for various scientific and technological applications.

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Section: Non-ionic Organic Nlo Crystalsmentioning

confidence: 99%

Organic Crystals for THz Photonics

et al. 2019

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“…Although crystalline films consisting of one molecular component have found diverse applications ( e . g ., optoelectronic devices), − relatively few examples are known with cocrystalline films. − The on-surface formation of highly organized multicomponent materials consisting of molecules, polymers, or biomolecules is still challenging, as it is difficult to predict their structure and properties. The formation of such films involves not only the supramolecular interactions between the structurally different components but also weak interactions with the solid interface.…”

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confidence: 99%

Noncovalent Bonding Caught in Action: From Amorphous to Cocrystalline Molecular Thin Films

et al. 2021

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We demonstrate the solvent-free amorphous-to-cocrystalline transformations of nanoscale molecular films. Exposing amorphous films to vapors of a haloarene results in the formation of a cocrystalline coating. This transformation proceeds by gradual strengthening of halogen-bonding interactions as a result of the crystallization process. The gas−solid diffusion mechanism involves formation of an amorphous metastable phase prior to crystallization of the films. In situ optical microscopy shows mass transport during this process, which is confirmed by cross-section analysis of the final structures using focused ion beam milling combined with scanning electron microscopy. Nanomechanical measurements show that the rigidity of the amorphous films influences the crystallization process. This surface transformation results in molecular arrangements that are not readily obtained through other means. Cocrystals grown in solution crystallize in a monoclinic centrosymmetric space group, whereas the on-surface halogenbonded assembly crystallizes into a noncentrosymmetric material with a bulk second-order nonlinear optical response.

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“…To reduce THz self-absorption and increase the interaction length, Cherenkov-type phase matching was achieved by combining thin film organic crystals with a Si prism. [276] To compensate for the phonon-induced absorption of organic crystals, a tandem structure of two complementary organic crystals was proposed, and an efficient broadband THz wave generation was experimentally demonstrated at 1 kHz, as shown in Figure 24d. [194] Compared to the use of single crystals, the use of an organic tandem THz generator leads to a 130% improvement in the electric field due to a 250% spectral enhancement at the phonon resonance with spectral engineering features.…”

Section: Thz Wave Generation In Nlo Organic Crystalsmentioning

confidence: 99%

Highly Nonlinear Optical Organic Crystals for Efficient Terahertz Wave Generation, Detection, and Applications

Kim

Kang

Puc

et al. 2021

Advanced Optical Materials

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ordering in the crystalline state should be simultaneously considered when designing organic π-conjugated crystals to achieve the desired physical properties. However, the prediction of the molecular ordering of organic π-conjugated chromophores in the crystalline state is still significantly difficult. This is because most organic π-conjugated chromophores exhibit several complex intermolecular and intramolecular interactions (and interionic interactions) with multiple possible molecular conformations during the self-assembling process in the crystalline state. [17,18] For each specific target application, a different targeted control of the molecular ordering of chromophores in the crystalline state is required, which is still an important issue in the molecular (and crystal) engineering of various organic π-conjugated crystalline materials.This issue is more critical for organic nonlinear optical (NLO) crystals and will be the focus of this review. Organic NLO crystals can be used in diverse nonlinear photonic applications, such as frequency down-and up-conversion, terahertz (THz) wave generation and detection, phase and amplitude electro-optic modulation, and high-speed telecommunication integrated optics. [19][20][21][22][23] Organic crystals must possess a noncentrosymmetric molecular ordering of chromophores to achieve second-order optical nonlinearity. However, in addition to the aforementioned complicated molecular interactions, the introduction of strong polar substituents (electron-donating groups (EDGs) and electron-withdrawing groups (EWGs)) on widely used push-pull π-conjugated chromophores to increase their molecular nonlinearity also increases their dipole moment. In many cases, a high dipole moment leads to a centrosymmetric ordering of chromophores with antiparallel dipole-dipole aggregation in the crystalline state (i.e., there is no macroscopic second-order optical nonlinearity). This tendency further complicates the development of new organic NLO crystals with large second-order optical nonlinearity. This is one of the reasons for only a few classes of organic crystals with state-of-theart optical nonlinearity being reported in the last few decades. Moreover, in addition to large macroscopic second-order optical nonlinearity, different NLO applications require different targeted physical properties (e.g., refractive index, dispersion of the refractive index, dielectric constant, and absorption coefficient) and crystal characteristics (e.g., direction of the polar axis, morphology, aperture size, thickness, and facets). Therefore, it Organic π-conjugated crystals with second-order optical nonlinearity are considerably attractive materials for diverse terahertz (THz) wave photonics. An overview of the research of organic nonlinear optical (NLO) crystals for THz wave generation, detection, and applications is provided here. First, the status of organic NLO crystals compared to other alternative THz materials is described. Second, the basic theory and requirements for organic THz generators and d...

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Organic Nonlinear Optical Single-Crystalline Thin Film Grown by Physical Vapor Deposition for Terahertz Generation

Cited by 11 publications

References 32 publications

Organic Crystals for THz Photonics

Organic Crystals for THz Photonics

Noncovalent Bonding Caught in Action: From Amorphous to Cocrystalline Molecular Thin Films

Highly Nonlinear Optical Organic Crystals for Efficient Terahertz Wave Generation, Detection, and Applications

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