Terahertz (THz) waves have attracted intensive researches in recent years due to their potential applications.
However, because of the long wavelength of this range, it is quite difficult to integrate the THz system in a small
size. Surface plasmons subwavelength optics opens a new way for fabrication of THz devices within wavelength
size. In this presentation, we use a simple subwavelength slit to generate the band gap in the THz range. The
transmission spectrum of this slit is measured by using the THz time domain spectroscopy. It was found that
when the slit width is narrow enough, the Fabry-Pèrot-like band gaps in the transmission spectrum will be
generated. The passband will be moved to the high frequency direction with the slit width narrowing. The
numerical simulations are also carried out based on the finite difference time domain method. It was found that
the simulation results correspond to the experiment results well. It is expected that this research can provide a
new way to fabricate THz device.