Title: Efficient optical-to-THz conversion organic crystals with simultaneous electron withdrawing and donating halogen substituents
Authors : Lee, Seung-Jun
Kang, Bong Joo
Shin, Myeong-Hoon
Lee, Seung-Chul
Lee, Seung-Heon
Jazbinsek, Mojca
Yun, Hoseop
Kim, Dongwook
Rotermund, Fabian
Kwon, O-Pil
Published in : Advanced optical materials
Volume(Issue) : 6
Issue : 2
Publisher / Ed. Institution : Wiley
Issue Date: 2018
License (according to publishing contract) : Licence according to publishing contract
Type of review: Not specified
Language : English
Subject (DDC) : 530: Physics
620.11: Engineering materials
Abstract: This study reports on highly efficient nonlinear optical ionic quinolinium crystals with various aromatic anions possessing different spatial volume for controlling the space‐filling characteristics and introducing halogen substituents having simultaneous electron‐withdrawing and electron‐donating effects. The quinolinium crystals with chloro and bromo substituents having simultaneous electron‐withdrawing and electron‐donating effects on anions exhibit perfect molecular ordering for optimizing the diagonal second‐order nonlinear optical response, while the fluoro substituent having relatively small electron‐donating effects on anions results in the absence of nonlinear optical response. Compared to widely used 4‐methylbenzenesulfonate, the chloro substituent on 4‐chlorobenzenesulfonate (CBS) results in decreasing π–π interactions between cations and anions. This leads on the one hand to an enhanced macroscopic nonlinear response and on the other hand to an increased strength of hydrogen bonds between anions, resulting in strong suppression of THz phonon vibration. In THz generation measurements with pump pulses at 1300 nm, 0.39 mm thick 2‐(4‐hydroxystyryl)‐1‐methylquinolinium 4‐chlorobenzenesulfonate (OHQ‐CBS) crystal exhibits excellent optical‐to‐THz conversion characteristics with 27 times higher peak‐to‐peak electric field and 3 times broader bandwidth than the well‐known 1.0 mm thick inorganic standard ZnTe crystal. In addition, compared to state‐of‐the‐art analogous quinolinium crystals with 4‐methylbenzenesulfonate, OHQ‐CBS crystal exhibits 1.8 times higher field.
Departement: School of Engineering
Organisational Unit: Institute of Computational Physics (ICP)
Publication type: Article in scientific Journal
DOI : 10.1002/adom.201700930
ISSN: 2195-1071
URI: https://digitalcollection.zhaw.ch/handle/11475/15443
Appears in Collections:Publikationen School of Engineering

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