New Terahertz Source for Wireless Communication

Terahertz source: Aperture in a metallic screen with a dielectric fiber placed on top acting as a magnetic dipole emitter when excited by a wave incident on the aperture. (Source: A. E. Miroshnichenko)

Electrical and optical engi­neers in Austra­lia have designed a novel platform that could tailor tele­communi­cation and optical trans­missions. Colla­borating scientists from the University of New South Wales in Sydney and Canberra, the Univer­sity of Adelaide, the Univer­sity of South Australia and the Austra­lian National Univer­sity experi­mentally demonstrated their system using a new trans­mission wave­length with a higher band­width capacity than those currently used in wireless communi­cation. These experi­ments open up new horizons in communi­cation and pho­tonics tech­nology.

Optical fibers are the front­runners in fast data trans­mission, with data encoded as micro­wave radia­tion. Current micro­wave wireless networks operate at a low giga­hertz frequency bandwidth. In our current digital age that demands speedy trans­mission of large amounts of data, the limi­tations of microwave band­widths become more increa­singly more apparent. Now, scientists examined terahertz radiation, which has shorter wave­lengths than micro­waves and there­fore has higher bandwidth capacity for data trans­mission. Further­more, terahertz radia­tion provides a more focused signal that could improve the efficiency of communi­cation stations and reduce power con­sumption of mobile towers. “I think moving into terahertz fre­quencies will be the future of wireless communications,” said Shaghik Atakara­mians. However, scientists have been unable to develop a tera­hertz magnetic source, a necessary step to harness the magnetic nature of light for tera­hertz devices.

The researchers inves­tigated how the pattern of terahertz waves changes on inter­action with an object. In previous work, Atakara­mians and colla­borators proposed that a magnetic terahertz source could theore­tically be produced when a point source is directed through a subwavelength fiber, a fiber with a smaller diameter than the radiation wave­length. Now, they experi­mentally demonstrated their concept using a simple setup – directing tera­hertz radia­tion through a narrow hole adjacent to a fiber of a subwave­length diameter. The fiber was made of a glass material that supports a circu­lating electric field, which is crucial for magnetic induction and enhance­ment in terahertz radiation.

“Creating tera­hertz magnetic sources opens up new directions for us,” Atakara­mians said. Terahertz magnetic sources could help the deve­lopment of micro- and nano­devices. For example, terahertz security screenings at airports could reveal hidden items and explosive materials as effec­tively as X-rays, but without the dangers of X-ray ionization. Another advantage of the source-fiber platform, in this case using a magnetic terahertz source, is the proven ability to alter the enhance­ment of the terahertz trans­missions by tweaking the system. “We could define the type of response we were getting from the system by changing the relative orien­tation of the source and fiber,” Atakara­mians said.

Atakara­mians emphasized that this ability to selec­tively enhance radiation isn’t limited to terahertz wave­lengths. “The conceptual signi­ficance here is applicable to the entire electro­magnetic spectrum and atomic radiation sources,” said Shahraam Afshar, the research director. This opens up new doors of deve­lopment in a wide range of nanotechno­logies and quantum techno­logies such as quantum signal processing. (Source: APL)

Reference: S. Atakaramians et al.: Enhanced terahertz magnetic dipole response by subwavelength fiber, APL. Phot. 3, 051701 (2018); DOI: 10.1063/1.5010348

Link: Inst. for Photonics and Advanced Sensing (IPAS), School of Physical Sciences, University of Adelaide, Adelaide, Australia

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