Publication type: Article in scientific journal
Type of review: Peer review (publication)
Title: Organic σ‐Hole containing crystals with enhanced nonlinear optical response and efficient optical‐to‐THz frequency conversion
Authors : Kim, Se‐In
Kim, Won Tae
Seok, Jin‐Hong
Jazbinsek, Mojca
Yoon, Woojin
Yu, In Cheol
Yun, Hoseop
Kim, Dongwook
Rotermund, Fabian
Kwon, O‐Pil
et. al : No
DOI : 10.1002/adom.201901840
Published in : Advanced Optical Materials
Issue Date: 2020
Publisher / Ed. Institution : Wiley
ISSN: 2195-1071
Language : English
Subject (DDC) : 621.3: Electrical engineering and electronics
Abstract: A new approach for the molecular design of highly efficient nonlinear optical organic crystals is proposed by introducing substituents that form σ‐holes on both nonlinear optical cationic chromophores and aromatic anions. Introducing chlorinated substituents, in which a relatively positive σ‐hole and a negative belt coexist, provides selective reduction capability of specific π–π intermolecular interactions and simultaneous multiple secondary bonding capabilities. This leads to a crystalline state with enhanced first‐order hyperpolarizability βcrystal of chromophores that favors parallel chromophore alignment and suppression of molecular vibrations, which are optimal characteristics for electro‐optic and nonlinear optical applications, including efficient THz wave generation. Compared to benchmark nonhalogenated and fluorinated analogous crystals with state‐of‐the‐art macroscopic optical nonlinearity, σ‐hole containing chloro‐quinolinium crystals exhibit up to two times higher macroscopic nonlinear optical response and remarkably different crystal characteristics. As a result, a 0.16 mm thick chloro‐quinolinium crystal exhibits ≈22 times higher optical‐to‐THz conversion efficiency than the widely used 1.0 mm thick ZnTe inorganic crystal. Moreover, chloro‐quinolinium crystals exhibit very broad THz spectra, up to 8 THz with significantly different THz spectral shape compared to benchmark organic crystals, which is attributed to different phase matching between optical and THz frequencies and molecular vibration motions.
URI: https://digitalcollection.zhaw.ch/handle/11475/19245
Fulltext version : Published version
License (according to publishing contract) : Licence according to publishing contract
Departement: School of Engineering
Organisational Unit: Institute of Computational Physics (ICP)
Appears in Collections:Publikationen School of Engineering

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