Optically tunable terahertz-band interference fringes shift

Optically tunable terahertz (THz)-band interference fringes shift in a polymer/silicon structure was investigated. We report an interference phenomenon formed by partial-through measurements and shift of periodic peaks in a terahertz time-domain spectroscopy system. When the terahertz beam passes through the sample edge, equally-spaced interference fringes are obtained in the frequency domain, and the interference fringes can be varied using an external continuous wave laser. This work offers the ability to observe THz-band interference fringes in the frequency domain; these interference fringes change with variations in the applied excitation light intensity.