Structural Design, Synthesis And Properties Of Pyridine-based Organic Nonlinear Optical Crystals

Organic nonlinear optical crystals have large second-order nonlinear coefficients,high electro-optic coefficients and low dielectric constants.In the THz field,THz radiation sources based on organic nonlinear optical crystals have the advantages of simple phase matching conditions,large bandwidth,and easy implementation,which have attracted widespread attention.The organic molecule D-?-A pyridine cation structure is redesigned to find a suitable combination of donor part and anion,and new derivatives are designed,which can further obtain crystal with excellent performance.Hydroxyl is a classic cationic electron donor,which promotes the arrangement of SHG active molecules and increases microscopic nonlinearity.In this paper,the hydroxyl group is set as a single donor part and placed in the meta position on the benzene ring to synthesize3-HBST crystals.Large-size and high-quality growth of 3-HBST crystal,the maximum size of the crystal can reach 13×7×3.5 mm3.The grown crystal was analyzed by synchrotron radiation white light topography and proved to be of good quality.In addition,the analysis of ultraviolet,visible and near infrared transmission,thermal stability and dielectric properties of 3-HBST crystal has good optical transmittance and thermal stability,and it is a potential organic nonlinear optics.Crystal material.In this paper,the multiplicity of donor groups is increased on the basis of hydroxyl groups,and new pyridine crystal materials HDST and DOTT are designed by introducing methyl and methoxy groups at different positions of the benzene ring in the cationic group.From crystal raw material synthesis to crystal growth to performance characterization,it is found that such materials have lower dielectric constant and dielectric loss,higher thermal stability and optical transmittance.Through the SHG test,it is found that the crystal has a second-order nonlinear signal generation.In addition,the anion of the pyridine derivative is designed,the benzenesulfonate anion is introduced,and the HDS-BS and HBS-BS are designed.The effect of the demethylated anion host on the performance of the crystal was explored,and the crystal material was tested in terms of optics,electricity and heat.It was found that the material had a lower dielectric constant and better thermal stability.With iodide ion as anion,3-HBSI,HDSI and DOTI were designed.The raw material synthesis and crystal growth of these organic iodinated pyridine derivatives have been tested and found that they have high optical transmittance in the Vis-NIR.