Last week, I found this nice experimental paper where the authors—a collection of people from Marburg, Tucson and Boulder—fabricate birefringent wave plates for terahertz electromagnetic radiation from paper.
Paper terahertz wave plates.
B. Scherger, M. Scheller, N. Vieweg, S. T. Cundiff and M. Koch.
Optics Express 19(25), 24884 - 24889 (2011).
Now, terahertz radiation can penetrate a few millimeters of some materials—human cells, fabrics and plastic included— and reflect back. This allows for non-invasive medical imaging and security scanning which may change our lives in a short period of time. Of course, terahertz light can be used in spectroscopy, communications, and the arts (one could see the various layers of an old painting or an old mural covered with plaster), to give an example.
It seems like the field of optical elements in the terahertz range is not as developed as one could think and Scherger and collaborators show that it is possible to create phase retarders for terahertz light by using form birefringence. That means they create a sub-wavelength pattern in a material; in this case, paper. Yes, they take some Xerox paper, cut it in a guillotine, stack it in a certain way so there's air in between the sheets and there you go!
I cannot wait to read about more terahertz optics with paper.
I cannot wait to read about more terahertz optics with paper.
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