Broadband terahertz dispersion control in hybrid waveguides.

Dispersion control is a key objective in the field of photonics and spectroscopy, since it enhances non-linear effects by both enabling phase matching and offering slow light generation. In addition, it is essential for frequency comb generation, which requires a phase-lock mechanism that is provided by broadband compensation of group velocity dispersion (GVD). At optical frequencies, there are several well-established concepts for dispersion control such as prism or grating pairs. However, terahertz dispersion control is still a challenge, thus hindering further progress in the field of terahertz science and technology. In this work, we present a hybrid waveguide with both broadband, tuneable positive and more than octave-spanning negative terahertz GVD on the order of 10 s/m, which is suitable for either intra- or extra cavity operation. This new terahertz device will enable ultra-short pulse compression, allow soliton propagation, improve frequency comb operation and foster the development of novel non-linear applications.