Generation of broadband THz pulses in organic crystal OH1 at room temperature and 10 K

Степанов, А. Л.; Ruchert, Clemens; Levallois, Julien; Erny, Christian; Hauri, Christoph P.

doi:10.1364/ome.4.000870

Cited by 20 publications

(7 citation statements)

References 26 publications

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“…The reason for the blue shift in the calculated spectra is attributed to the temperature difference, 0 K, considered in the calculation (although the crystal structure used in the calculations is measured at 293 K), while the experiment is performed at 298 K. Compared to high temperature, shorter interaction distances at low temperature result in increased force constants of vibrations, which leads to a blue shift of absorption peaks (i.e., increasing frequency). This effect in the THz range has also been experimentally observed in ref : the frequency of absorption peaks increases with decreasing the measured temperature. However, even with a small blue shift, the calculation results of vibrational absorption of OH1 crystals are still very well-matched with experimental results.…”

Section: Resultssupporting

confidence: 83%

Terahertz Phonon Modes of Highly Efficient Electro-optic Phenyltriene OH1 Crystals

Kim

Lee

et al. 2016

J. Phys. Chem. C

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Understanding the origin of the phonon modes of highly efficient electro-optic crystals is very important for designing materials and for optimizing their photonic applications. Here we investigate the origin of phonon modes in the 0.1−15 THz range of the benchmark electrooptic OH1 (2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2enylidene)malononitrile) crystal, which is interesting due to its large electro-optic coefficient and high THz-wave generation efficiency. The phonon modes (and vibrational absorption properties) of OH1 crystals are evaluated theoretically by periodic density functional theory and also experimentally by THz absorption spectroscopy. The theoretical calculations are well-matched with experimental results. The THz absorption properties are highly anisotropic; the amplitude of the vibrational absorption is the largest along the polar c-axis compared to the other two crystallographic axes. For comparison, the vibrational absorption modes of the OH1 molecule in the gas phase are also calculated. The calculated vibrational absorption spectrum of OH1 crystalline powder appears similar to that of the OH1 molecule in the gas phase. However, the molecular vibrational motions in the crystalline state are coupled motions of vibrational motions in the gas phase. Interestingly, the vibrational mode of the torsion of the O−H bond with the largest absorption strength in the gas phase is in the crystal inhibited due to the crystal field effect. The origin of the intense phonon modes of OH1 crystals is mainly related to relatively strong distortions of the push−pull π-conjugated system including electron donor and acceptor groups.

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Section: Resultssupporting

confidence: 83%

Terahertz Phonon Modes of Highly Efficient Electro-optic Phenyltriene OH1 Crystals

Kim

Lee

et al. 2016

J. Phys. Chem. C

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“…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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“…This difference between calculation and experiment may result from the structural optimization on a fixed unit cell [34][35][36] and/ or thermal dissipations by unharmonic vibrations and mixing among neighboring vibrations. [37][38][39][40][41] Note that the experimental results based on THz time-domain spectroscopy may also only have a limited accuracy. Nevertheless, these delicate differences do not have a significant influence on our research goal of understanding the origin of molecular vibrations, which contribute to the major absorptions in the experiment.…”

Section: Solid-state Vibrations Of Acentric Molecular Salt Crystalsmentioning

confidence: 99%

Solid‐State Molecular Motions in Organic THz Generators

Kim

Park

Seok

et al. 2020

Advanced Optical Materials

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Organic nonlinear optical salt crystals are widely used as efficient broadband THz generators. Although solid state molecular motions of organic crystals can greatly influence THz generation characteristics, their origin and effects on THz photonics are not clearly identified. In this work, the origin of solid‐state molecular motions of the state‐of‐the‐art nonlinear optical organic salt crystals and their effects on THz generation characteristics are theoretically investigated. A model crystal, HMQ‐TMS (2‐(4‐hydroxy‐3‐methoxystyryl)‐1‐methylquinolinium 2,4,6‐trimethylbenzenesulfonate) with large macroscopic optical nonlinearity, which is very attractive for intense broadband and narrowband THz wave generation, is chosen. The solid‐state molecular vibrations of HMQ‐TMS crystals can be classified in three frequency regions: phonon mode region, intramolecular motion region, and their mixing region. For the first time for ionic organic crystalline THz generators, the contributions of cationic chromophores and anionic matchmakers on each of vibrational modes are quantitatively separated. In addition, the influence of solid‐state molecular vibrations of HMQ‐TMS crystals on the generated THz spectra is investigated. These results provide an essential information for design of new organic nonlinear optical salt crystals for THz generators as well as detectors and for optimization of THz generation performance.

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Generation of broadband THz pulses in organic crystal OH1 at room temperature and 10 K

Cited by 20 publications

References 26 publications

Terahertz Phonon Modes of Highly Efficient Electro-optic Phenyltriene OH1 Crystals

Terahertz Phonon Modes of Highly Efficient Electro-optic Phenyltriene OH1 Crystals

Organic Crystals for THz Photonics

Solid‐State Molecular Motions in Organic THz Generators

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