Broadband THz-wave generation with organic crystals OHI and DSTMS

摘要

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 [1-4]. 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) [1-4], 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) [5], 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 [6]. THz wave generation using optical rectification has been previously demonstrated using DSTMS [5] and OH1 [6] up to about 3 THz.