New benzothiazolium crystals with very large off-diagonal optical nonlinearity. (August 2021)

• Record Type: Journal Article
• Authors: Kim, Seung-Jun; Yu, In Cheol; Lee, Ji-Ah; Kim, Won Tae; Jazbinsek, Mojca; Yoon, Woojin; Yun, Hoseop; Rotermund, Fabian; Kwon, O-Pil
• Is Part Of: Dyes and pigments. Volume 192(2021)
• Publication Date: 2021-08
• Subjects: Nonlinear optics -- Organic crystals -- Chromophores -- THz wave generation; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2021.109433
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: In this study, we develop new organic benzothiazolium crystals possessing very large off-diagonal optical nonlinearity. In these crystals, benzothiazolium-based 2-(4-(4-(hydroxymethyl)piperidin-1-yl)styryl)-3-methylbenzothiazol-3-ium (PMB) cations with large molecular optical nonlinearity are incorporated with two anions: 4-(trifluoromethoxy)benzenesulfonate (TFO) with an orthogonal non-planar shape and 5-bromothiophene-2-sulfonate (BTS) with a planar shape. Both PMB-TFO and PMB-BTS crystals exhibit state-of-the-art off-diagonal effective hyperpolarizability (~105 × 10 −30 esu) that results from the V-shape and X-shape alignments of PMB chromophores, respectively. Newly developed PMB crystals indicate excellent characteristics for second-order nonlinear optical applications such as difference-frequency generation (e.g. optical rectification) and sum-frequency generation (e.g. second-harmonic generation), which are comparable to current benchmark organic crystals. Graphical abstract: Newly developed PMB-based crystals exhibit state-of-the-art off-diagonal effective hyperpolarizability and show excellent frequency conversion characteristics, including efficient optical-to-THz conversion using the large off-diagonal optical nonlinearity. Image 1 Highlights: New benzothiazolium crystals exhibit state-of-the-art off-diagonal optical nonlinearity. Large off-diagonal optical nonlinearity of new benzothiazolium crystals originates from different ordering of chromophores. New benzothiazolium crystals indicate excellent performance in second-order nonlinear optical processes.