Intense THz Source of Sub-Cycle Pulses with Tunable Elliptical Polarization

We propose a new THz source based on a large aperture photoconductive antenna for the generation of intense THz waves with tunable elliptical polarization. We designed an interdigitated structure with vertical and horizontal electrodes to produce half-cycle THz pulses with horizontal and vertical polarizations, respectively. A time delay between the two polarizations is introduced using a quartz window deposited onto the parts of the antenna with horizontal electrodes forming a phase mask. We demonstrate the generation of sub-cycle THz pulses with tunable elliptical polarization and a 70 kV/cm electric field. We show that the polarization state can be varied from linear to quasi-circular.