Time and Frequency Resolved THz Spectroscopy of Micro- and Nano-Systems

Terahertz technology [1], at present a dynamically developing field, was enabled by advances in ultra-short pulse lasers and semiconductor coherent sources in the frequency range of 1–50 THz. The extensive activities are focused on THz optics, spectrally bright sources, and detectors. The terahertz time-domain spectroscopy and terahertz imaging are main fields, where terahertz technology finds application. In this contribution we present our recent results in the field of terahertz time-domain spectroscopy (THz-TDS) applied to microand nanosystems and in the development of THz optics. First, we report on a broadband absorptive anti-reflection coating that suppresses the reflection of terahertz pulses within an electro-optic detector. The anti-reflection coating is made of a thin chromium layer. We prove functionality of the layer in the THz time-domain spectroscopy. We estimate for the first time the complex index of refraction of such layers in the spectral range of 0.1–4 THz. Second, in the contribution we also report on a complex permittivity of nanoscale composite material — the single-wall carbon nanotube (SWCNT) mats measured by THz-TDS at frequencies from 0.1 THz up to 4 THz.