Linear to Circular Polarization Conversion of Terahertz Wave Using Metallic Helix Array

We developed a 2D array of 3D metallic helix which converts linearly polarized terahertz (THz) wave into circularly polarized THz wave and acts as a broadband THz wave polarizer. It covers the frequency range from 140 GHz to 250 GHz, close to one octave. We made two different arrays which consist of left-handed and right-handed metallic helices and we confirmed that these arrays change the linearly polarized THz wave into right-hand and left-hand circularly polarized THz wave respectively.