Polarization response of two-dimensional metallic photonic crystals studied by terahertz time domain spectroscopy

The polarization characteristics of the THz wave transmitted through the two-dimensional metallic photonic crystal (2D-MPC) are investigated. The 2D-MPC, we used here, is a thin conductive screen perforated periodically with circular holes. We measured the polarization characteristics of the THz wave using THz time-domain spectroscopy with wire-gird polarizers. In this system, we can detect the temporal polarization behavior of the THz wave and describe them in 3D-trajectory plot. The polarization rotation of the detected THz wave is observed although the incident THz wave is linearly polarized. This indicates that the 2D-MPC acts as a wave plate for the THz wave. It is also observed that this polarization rotation of the transmitted THz wave is highly sensitive to the incident angle.