Nichtlinear-Optische Erzeugung von Dauerstrich-Terahertzwellen (English shop)

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This thesis addresses the nonlinear-optical generation of narrowband continuous-wave terahertz waves. For the first time, a terahertz optical parametric oscillator is presented that is based on periodically poled lithium niobate – a standard material of nonlinear optics – and is tunable in the range of 1–3 THz with output powers of up to 70 µW. The limits of power and tunability are set by the high terahertz absorption of the material.

A material that has only recently become available and that is promising due to its considerably lower absorption is orientation-patterned gallium arsenide for quasi-phase matching. The second source, presented here for the first time, is a doubly resonant optical parametric oscillator with intracavity difference-frequency mixing in gallium arsenide. It is shown that the tunability can be extended from the experimentally demonstrated 1–4.5 THz to up to 15 THz and that the output power can be increased into the milliwatt range through further improvements in the quality of the orientation-patterned gallium arsenide. The combination of tunability and power of the continuous-wave terahertz sources presented in this work can facilitate the transfer of high-resolution spectroscopic measurement techniques into the terahertz range.