Publication type: Article in scientific journal
Type of review: Peer review (publication)
Title: Wide‐bandgap organic crystals : enhanced optical‐to‐terahertz nonlinear frequency conversion at near‐infrared pumping
Authors: Kim, Deokjoong
Kim, Won Tae
Han, Jae‐Hyun
Lee, Ji‐Ah
Lee, Seung‐Heon
Kang, Bong Joo
Jazbinsek, Mojca
Yoon, Woojin
Yun, Hoseop
Kim, Dongwook
Bezouw, Stein
Campo, Jochen
Wenseleers, Wim
Rotermund, Fabian
Kwon, O‐Pil
et. al: No
DOI: 10.1002/adom.201902099
Published in: Advanced Optical Materials
Volume(Issue): 8
Issue: 10
Pages: 1902099
Issue Date: 16-Mar-2020
Publisher / Ed. Institution: Wiley
ISSN: 2195-1071
Language: English
Subjects: THz Photonics
Subject (DDC): 621.3: Electrical, communications, control engineering
Abstract: Enhanced terahertz (THz) wave generation is demonstrated in nonlinear organic crystals through refractive index engineering, which improves phase matching characteristics substantially. Unlike conventional low‐bandgap nonlinear organic crystals, the newly designed benzimidazolium‐based HMI (2‐(4‐hydroxy‐3‐methoxystyryl)‐1,3‐dimethyl‐1H‐benzoimidazol‐3‐ium) chromophore possesses a relatively wide bandgap. This reduces the optical group index in the near‐infrared, allowing better phase matching with the generated THz waves, and leads to high optical‐to‐THz conversion. A unique feature of the HMI‐based crystals, compared to conventional wide‐bandgap aniline‐based crystals, is their remarkably larger macroscopic optical nonlinearity, a one order of magnitude higher diagonal component in macroscopic nonlinear susceptibility than NPP ((1‐(4‐nitrophenyl)pyrrolidin‐2‐yl)methanol) crystals. The HMI‐based crystals also exhibit much higher thermal stability, with a melting temperature Tm above 250 °C, versus aniline‐based crystals (116 °C for NPP). With pumping at the technologically important wavelength of 800 nm, the proposed HMI‐based crystals boost high optical‐to‐THz conversion efficiency, comparable to benchmark low‐bandgap quinolinium crystals with state‐of‐the‐art macroscopic nonlinearity. This performance is due to the excellent phase matching enabled by decreasing optical group indices in the near‐infrared through wide‐bandgap chromophores. The proposed wide‐bandgap design is a promising way to control the refractive index of various nonlinear organic materials for enhanced frequency conversion processes.
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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