Generation of terahertz optical skyrmion by interference system

We report the experimental generation of optical skyrmions in the terahertz (THz) region. Using a frequency-tunable two-path interference system, we generated skyrmions at 3–4 THz by superposing a Gaussian beam and an optical vortex with orthogonal circular polarizations. The resulting polarization textures were quantitatively characterized through Stokes parameter analysis and skyrmion number evaluation, demonstrating high topological fidelity. Two control methods were demonstrated: inversion of circular polarization handedness via quarter-wave plate rotation and reversal of orbital angular momentum sign by flipping the spiral phase plate, enabling robust switching between Néel-type and anti-type configurations. Furthermore, we observed the trajectory of the THz beam spot at the focal plane as a function of the phase delay induced by phase modulation.