Terahertz Emitters and Detectors for Radially and Azimuthally Polarized Beams

摘要

We present photoconductive emitters and detectors for radially and azimuthally polarized terahertz beams. Microstructured electrodes consisting of concentric rings serve as antennas for radially polarized beams. Electrode patterns consisting of radially arranged segments are employed for the antennas for azimuthally polarized beams. A second periodic structure is used to prevent destructive interference of THz wavelets of opposite polarization. Beam profiles are detected for divergent beams in proximity to the emitter as well as for refocused beams. The THz beams have a donut-like intensity distribution and the beam profiles can be quantitatively described as lowest order Bessel-Gauss modes. Furthermore we demonstrate that detection antennas of similar patterning are selective for detection of particular modes.