Wide‐bandgap organic crystals : enhanced optical‐to‐terahertz nonlinear frequency conversion at near‐infrared pumping
| Autor: | 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, Han, Jae-Hyun, Lee, Ji-Ah, Lee, Seung-Heon, van Bezouw, Stein, Kwon, O-Pil |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
business.industry Terahertz radiation Band gap Physics Near-infrared spectroscopy Nonlinear optics 02 engineering and technology THz Photonics 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences Electronic Optical and Magnetic Materials Nonlinear system 621.3: Elektro- Kommunikations- Steuerungs- und Regelungstechnik Frequency conversion Optoelectronics 0210 nano-technology business |
| Zdroj: | Advanced Optical Materials |
| ISSN: | 2195-1071 |
| Popis: | Enhanced terahertz (THz) wave generation was demonstrated in nonlinear organic crystals through refractive index engineering, which improved 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 exhibited 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 boosted 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. |
| Databáze: | OpenAIRE |
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