Analytical model of Gouy phase influence in terahertz time-domain spectroscopy

摘要

Transmission measurements using THz time-domain spectroscopy (THz-TDS) are often affected by amplitude and phase changes due to spatial properties of the focused beam. This axial anomaly is called the complex Gouy phase and significantly influences measurements as well as determination of material parameters of a measured sample. The method of the Gouy phase shift compensation has been published in our previous paper [1]. In this paper, we suggest a model of spatial-frequency dependence of the complex phase with additional effects of non-axial components due to focusing on a finite size detector.