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An optoelectronic contactless method by THz time domain spectroscopy(THz-TDS, in the frequency range 0.5-3.0 THz) has been used to measure the absorption, dispersion, and reflectance of $FeCl_{3}-dopedpoly(2-methoxy-5-(2'-ethyl)hexyloxy-p-phenylene vinylene)$ [MEHPPV]film. The measured data fit well to Lorentz oscillator (LO) model indicating that free carriers are negligible though the system is fairly conducting (similar to 0.1 S/cm) at room temperature. The large value of the coupling constant $(\Omega_{p1}/2 \pi = 14.7 THz)$ in LO model indicates that intra-chain localization of carriers is rather strongand the inter-chain transport is quite weak.

Absorption and dispersion of singlewalled carbon nanotube films were measured using an optoelectronic THz beam system for THz time-domain spectroscopy. The anisotropically aligned nanotube films were prepared through simple mechanical squeezing with a bar coater. The angle-dependent absorption and dispersion values were then measured. Results indicate that the index of refraction decreases with increasing frequency (0.1–0.8 THz), whereas the real conductivity increases with increasing frequency. The real conductivity measured is not congruent with the simple Drude model, but it follows a Maxwell–Garnett model, where the nanotubes are embedded in a dielectric host.

Characterizations of singlewalled carbon nanotube (SWCNT) films were measured using an optoelectronic terahertz (THz) time-domain spectroscopy system. The conductivities of SWCNT were found to increase as frequency increases. The purified SWCNT film was likewise revealed to have larger conductivity than unpurified SWCNT film. The anisotropically aligned SWCNT films were found to have higher conductivities when film polarization is parallel to THz pulse polarization.