Longitudinal fields in focused terahertz beams


Longitudinal fields in focused terahertz beams

Winnerl, S.; Hubrich, R.; Mittendorff, M.; Schneider, H.; Helm, M.

In textbooks electromagnetic waves are often described as infinitely extended plane waves, which are of purely transverse character. For beams of finite size, however, also longitudinal fields are expected. In case of focused radially polarized beams, the longitudinal fields can actually be stronger as compared to the transverse components. This has been found in experiments recording the intensity of near-infrared beams. In our study we directly record the electric field of single cycle terahertz pulses of radial and linear polarization. This enables us to reveal the phase relation between longitudinal and transverse fields. The obtained value of pi/2 is of universal nature as it does not depend on the type of mode, frequency or focusing condition. Additionally we demonstrate that the longitudinal components of radially polarized beams exhibit superior focusing properties.

Keywords: radially polarized fields; longitudinal electromagnetic fields; terahertz radiation

  • Lecture (Conference)
    DPG-Frühjahrstagung, 10.-15.03.2013, Regensburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19706
Publ.-Id: 19706