The dramatic progress over recent years in the sources and detectors of ultrashort electromagnetic pulses in the THz spectral region has opened up many new possibilities in far-infrared spectroscopy. Control and measurement of the temporal, spatial, and spectral characteristics of such pulses have been demonstrated in many experiments and applications. Another fundamental property of the radiation has, however, been largely ignored: control of the polarization state of the THz pulses. In this paper, we demonstrate the production of circularly polarized (CP), single-cycle THz pulses. The results are of interest from the point of view of basic electromagnetism, because the pulses exhibit a time evolution of the electrical field vector that differs significantly from the well-known behavior for monochromatic radiation. The production and measurement of CP radiation is also of considerable interest for THz spectroscopy. It permits the ready characterization of materials for which the normal modes of propagation are circularly polarized, including such important cases of chiral and magnetized materials.
展开▼
