The spacing between the holes in this metal film determines the wavelength of terahertz radiation that passes through.
Filtering Terahertz Frequencies
A new type of filter could make extremely fast wireless communication devices possible
Source: “Transmission Resonances through Aperiodic Arrays of Subwavelength Apertures”
Tatsunosuke Matsui et al.
Nature 446: 517-521
Results: Researchers at the University of Utah have designed a perforated stainless-steel film that restricts the frequencies of terahertz radiation passing through it. In effect, the film is a simple terahertz filter, a potential precursor to terahertz communication devices.
Why it matters: The filter could provide a way to control terahertz radiation in future wireless devices. Though still years from commercialization, wireless networks that use this radiation–which technically ranges from about 100 gigahertz to 10 terahertz–could carry much more data than existing networks, speeding up wireless Internet links by a factor of a thousand. Terahertz transmission would be most useful for relatively short-range communication–between devices in a room, for example.
Methods: The new filter is made of stainless steel with arrays of holes in it. When terahertz radiation passes through the holes, it propagates as a terahertz wave with a few narrow frequency bands; the frequencies emitted depend on the spacing of the holes. Where previous studies had assumed that uniform arrays were necessary for terahertz filtration, the Utah researchers used irregular arrays of perforations, allowing several different frequencies of radiation to pass through the filter at the same time.
Next steps: The researchers will now try to build terahertz communication devices based on the principles demonstrated by their work thus far.