Asymmetric Offset Multi-Electrode Photoconductive Antenna for Terahertz Wave Polarization Control

Conventional multi-electrode photoconductive antennas (PCAs) can only radiate linearly polarized terahertz waves with polarization angles in increments of 45°, limiting their use for the characterization of diverse anisotropic material. We propose a multi-electrode PCA with an asymmetric offset electrode structure, enabling linear polarization at 30° increments. Furthermore, the electrode design is optimized with a semicircular geometry to reduce electric field concentration at electrode edges, effectively suppressing electrical breakdown. Simulation results demonstrate that the applied bias voltage can be increased to 70 V, yielding a radiation power of 14.5 µW. The proposed design thus achieves dynamic polarization control without sacrificing output power.