Title: Terahertz phonon mode engineering of highly efficient organic terahertz generators
Authors : Lee, Seung-Heon
Kang, Bong Joo
Yoo, Ba-Wool
Lee, Seung-Chul
Lee, Seung-Jun
Jazbinsek, Mojca
Yun, Hoseop
Rotermund, Fabian
Kwon, O-Pil
Published in : Advanced Functional Materials
Volume(Issue) : 27
Issue : 14
Pages : 1605583
Publisher / Ed. Institution : Wiley
Issue Date: 2017
License (according to publishing contract) : Licence according to publishing contract
Type of review: Peer review (Publication)
Language : English
Subject (DDC) : 530: Physics
540: Chemistry
620: Engineering
Abstract: For terahertz (THz) wave generators based on organic electrooptic crystals, their intrinsic phonon modes are playing an essential role in THz generation characteristics. Here, this study proposes an effective design strategy for THz phonon mode engineering of organic electrooptic salt crystals for efficient optical-to-THz frequency conversion. To reduce phonon-mode intensity, strongly electronegative trifuoromethyl group acting as strong hydrogen-bond acceptor is incorporated into molecular anions. New 2-(4-hydroxy-3-methoxystyryl)-1-methylquinolinium 4-(trifuoromethyl)benzenesulfonate (HMQ-4TFS) crystals exhibit a relatively small absorption coefficient in the THz spectral range between 0.5 and 4 THz, which is attributed to suppressed molecular vibrations due to strong hydrogen bonds involving the 4TFS anion. In addition, HMQ-4TFS crystals possess a very large macroscopic optical nonlinearity, comparable (or even higher) to benchmark stilbazolium crystals. Based on the low-intensity THz phonon modes and the large optical nonlinearity, a 0.37 mm thick HMQ-4TFS crystal pumped with 150 fs infrared laser pulses facilitates very efficient THz wave generation by optical rectification, delivering 23 times higher peak-to-peak THz electric eld than the widely used standard inorganic ZnTe crystal (1.0 mm thick) and a broader spectral bandwidth. Therefore, strongly electronegative groups introduced into molecular salt electrooptic crystals provide a very promising design strategy of THz phonon mode engineering for developing intense broadband THz sources.
Departement: School of Engineering
Organisational Unit: Institute of Computational Physics (ICP)
Publication type: Article in scientific Journal
DOI : 10.1002/adfm.201605583
ISSN: 1616-301X
URI: https://digitalcollection.zhaw.ch/handle/11475/4154
Appears in Collections:Publikationen School of Engineering

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