Stable growth of large-size organic 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate crystal and its optical, dielectric and THz properties

Results of an experimental study on the stable growth of large-enough and crack-free organic nonlinear optical 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST) crystal by seed crystal fixing method with reasonable growth speed are reported. It is found that large and high-quality crystal with size of 25 x 22 x 2 mm(3) under lower concentration of the solution for a growth rate of 0.47 mm/day can be obtained. Terahertz (THz) waves based on the crystal were generated using difference frequency generation (DFG) method. Tunable THz-wave in the broad range of 0.3-19.6 THz was obtained. At 18.9 THz, the maximum output energy of THz waves reaches 870.4 nJ/pulse, and the corresponding energy conversion efficiency is 1.036 x 10(-4). It is also found that the single-pulse energy of DAST crystal varies with the crystal thickness (140, 400 and 610 mu m). DAST crystals with a thickness of 140 mu m have high single-pulse energy. The UV-vis-NIR spectrum, dielectric properties, photoluminescence spectrum, and Raman spectra of crystalline samples were also investigated. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The experimental results show that stable growth of large and crack-free DAST crystals can be achieved using the seed crystal fixing method, with high quality crystals obtained at lower solution concentrations and reasonable growth speeds. THz waves were generated based on these crystals using the DFG method, with tunable waves in a broad range and high energy conversion efficiency. The single-pulse energy of the DAST crystal was also found to vary with crystal thickness, with crystals of 140 µm thickness having high single-pulse energy. Additionally, various properties and spectra of the crystalline samples were investigated.