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

Abstract 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 × 22 × 2 mm3 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 × 10−4. It is also found that the single-pulse energy of DAST crystal varies with the crystal thickness (140, 400 and 610 μm). DAST crystals with a thickness of 140 μm have high single-pulse energy. The UV-vis-NIR spectrum, dielectric properties, photoluminescence spectrum, and Raman spectra of crystalline samples were also investigated.