In this thesis, I present studies in the field of terahertz [THz] spectroscopy. It covers both the generation and detection of ultra-fast broadband THz pulses, as well as the transmission properties of vertically grown multi-walled carbon nanotube forests [MWCNTs]. We have found that these vertically grown MWCNTs respond strongly to THz radiation and exhibit an anisotropic optical response. The analysis done was a simplified model that is frequency-indepedent, which led to discrepancies between the theoretical and experimental data. This suggests that the response of the CNTs is frequency-dependent, and further, more complex analysis is required to fully describe their properties. / Graduation date: 2013