Deviation of optical constants extracted in terahertz transmission spectroscopy

We present a simulation with a Lorentz oscillator model to evaluate the accuracy of the extracted optical constants in terahertz transmission spectroscopy. The contributions of various error sources including the deflection of the incident angle, the delay-line timing error, and two other kinds of noises are analyzed. It is revealed that the influence of the deflection angle is an approximate parabolic dependence. The delay-line timing uncertainty introduces an exponential frequency dependence in the deviation of the extinction coefficient and a distinct change in the refractive index data in the resonant region. When background and 1/f noises are introduced, the deviation mainly concentrates in the resonant region.