Marburg, Germany--A terahertz polarization rotator that is so simple it can be fabricated by school children has been developed by scientists at the University of Marburg (Philipps-Universität Marburg). Reported in a recent issue of Optics Express (B. Scherger et al. Optics Express 19, 24884 (2011)) by professor Martin Koch's group, the wave plate consists of paper and is based on the principle of form birefringence.
Thin strips of paper are stacked in a way that there is a thin gap of air between every other piece. If polarized terahertz waves transmit through this paper structure under a certain angle, their polarization state is turned or rotated. For certain frequencies, the rotation can be as large as 90 degrees. In this case, the device acts as a half wave plate. The paper wave plate is more efficient and markedly cheaper than more elaborately produced counterparts, such as those made from metamaterials.
In order to prove that production of this terahertz component is as easy as child's play, Benedikt Scherger and Martin Koch visited a local kindergarten near Marburg. The preschoolers devotedly produced paper strips that were combined to form a wave plate. Afterwards, the children were able to see the operational reliability of the wave plate's construction in the laboratory.
SOURCE: Philipps-Universität Marburg; http://idw-online.de/en/news456160