We report detailed measurements of the cross-polarized radiation from lens-coupled terahertz dipole antennas, of the sort commonly used in terahertz time-domain spectroscopy. We compare two different antenna geometries and measure both polarization components as a function of emission angle. The qualitative features of these patterns are not specific to one particular emitter geometry but appear to be generally characteristic of these lens-coupled systems. These measurements are used to determine the angle-dependent ellipticity of the emitted terahertz beam. We conclude that a low f-number collection system unavoidably results in a beam with a small but measurable ellipticity. This has important implications for any measurements in which a purely linearly polarized wave is required.
© 2001 Optical Society of AmericaFull Article | PDF Article
Andreas Gürtler, Carsten Winnewisser, Hanspeter Helm, and Peter Uhd Jepsen
J. Opt. Soc. Am. A 17(1) 74-83 (2000)
J. V. Rudd, Jon L. Johnson, and Daniel M. Mittleman
Opt. Lett. 25(20) 1556-1558 (2000)
A. Boh Ruffin, Joan Decker, Laurent Sanchez-Palencia, Lénaic Le Hors, John F. Whitaker, Theodore B. Norris, and J. V. Rudd
Opt. Lett. 26(10) 681-683 (2001)