Broadband THz-wave generation with organic crystals OHI and DSTMS

Organic electro-optic crystals are efficient THz-wave generators using optical rectification (OR) or difference-frequency generation (DFG) of various fs or ns/ps pump laser sources in the infrared. This is due to their higher second-order susceptibilities compared to inorganics, combined with excellent phase-matching possibilities. However, most of the efforts in the past have focused only on the generator crystal DAST (4-N, N-dimethylamino-4´-N´-methyl-stilbazolium tosylate), because of the lack of alternative crystals with similarly high figures of merit and possibilities for growth of high-quality single crystals. We investigate THz interactions using recently developed materials, stilbazolium salt DSTMS (4-N, N-dimethylamino-4´-N´-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate), which is a DAST derivative with improved properties for THz-wave generation, as well as phenolic polyene OH1 (2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile), which is hydrogen bonded crystal and an important alternative for stilbazolium salts due to the low THz absorption and even better figures of merit for THz wave generation. THz wave generation using optical rectification has been previously demonstrated using DSTMS and OH1 up to about 3 THz.