Characterization of Organic nonlinear optical crystals for THz applications

This work evaluated the effects of humidity and temperature on organic nonlinear optical crystals. To assess the effect of humidity, we compared THz wave generation before and after exposure to a temperature of $30^{\circ}\mathrm{C}$ and a humidity of 80 % for 10 weeks. THz wave output decreased for the DAST crystal but not for the DASC or OH1 crystals. Regarding the effect of temperature, we evaluated the temperature dependence on the electro-optic (EO) effect. When evaluated using one DAST crystal, the EO signal changed periodically with temperature fluctuations. In comparison, when the a-axes of the two DAST crystals were orthogonal, the EO signal did not fluctuate. These results show that the properties of organic nonlinear optical crystals need to be understood and optimized.