Terahertz characterization of multi-walled carbon nanotube films

Multi-walled carbon nanotube films are characterized using terahertz time-domain spectroscopy. Both transmission and reflection experiments are performed in order to measure both the complex refractive index and the wave impedance. This method allows simultaneous extraction of both the permittivity (ε=ε′−iε″) and permeability (μ=μ′−iμ″) without any assumptions. Experimental results are obtained from 50 to 370 GHz and compared well with the microwave data (8–50 GHz) of the same sample measured using a vector network analyzer. The measured complex permittivity can be fitted with a Drude–Lorentz model in the 8–370 GHz frequency range.