Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Millimeter waves for the last mile

22.11.2018

The high oscillation frequencies of light waves make them ideally suited to fast data transmission. They can be sent through optical fibres and easily carry hundreds of billions of bits (Gigabits) per second.

The "last mile" from a central fibre optic cable to the internet socket at home, however, is the most difficult and expensive. Some alternatives, for instance 4/5G mobile telephony, are cheaper, but they cannot provide all users simultaneously with the extremely high transmission rates required by today's data-hungry applications such as streaming TV.


In the new modulator developed at ETH Zurich, millimeter wave signals (blue) are received by an antenna and converted into optical signals (red) inside the tiny slot in the middle. The device works without a power supply and is less than a millimeter in size.

Credit: ETH Zurich / Jürg Leuthold

Jürg Leuthold, professor at the Institute for Electromagnetic Fields at ETH Zurich, and his collaborators have now, with support by colleagues at the University of Washington in Seattle, developed a novel light modulator that will make it possible in the future to cover the last mile efficiently and at a low cost with high-frequency microwaves - so called millimetre waves - and hence high data transmission rates.

Light modulator without electronics

To transfer data encoded in optical fibres through a variation in the light intensity onto millimetre waves, very fast - and hence expensive - electronic components are needed. In the opposite direction, millimetre waves first have to be received by an antenna, then amplified and mixed down to baseband and finally injected into a light modulator, which translates the data contained in the radio waves back into light pulses.

Leuthold and his colleagues have now succeeded in building a light modulator that works entirely without batteries and electronics.

"That makes our modulator completely independent of external power supplies and, on top of that, extremely small so that it can, in principle, be mounted on any lamppost. From there, it can then receive data via microwave signals from individual houses and feed them directly into the central optical fibre", explains Yannick Salamin, a PhD student who made crucial contributions to the development of the new modulator.

Modulation through plasmons

The modulator built by the ETH researchers consists of a chip measuring less than a millimetre that also contains the microwave antenna. That antenna receives the millimetre waves and converts them into an electric voltage. The voltage then acts on a thin slot at the centre of the chip - the actual heart of the modulator. There, a narrow slit, just a few micrometres long and less than a hundred nanometres wide, is filled with a material that is particularly sensitive to electric fields.

The light beam from the fibre is fed into that slit. Inside the slit, however, the light propagates - differently from the fibre optic cable or air - no longer as an electromagnetic wave, but as a so-called plasmon. Plasmons are hybrid creatures made of electromagnetic fields and oscillations of electric charge at the surface of a metal. Owing to this property, they can be confined much more tightly than light waves.

The electrically sensitive ("nonlinear") material inside the slit ensures that even the tiniest electric field created by the antenna will strongly influence the propagation of the plasmons. That influence on the oscillatory phase of the waves is conserved when the plasmons are converted back into light waves at the end of the slit.

In this way, the data bits contained in the millimetre waves are transferred directly onto the light waves - without taking a detour through electronics, and without any external power. In a laboratory experiment with microwave signals at 60 Gigahertz, the researchers were able to demonstrate data transmission rates of up to 10 Gigabits per second over a distance of five metres, and 20 Gigabits per second over one metre.

Cheap and versatile

Besides the tiny size and the negligible energy consumption, the new modulator has a number of further advantages. "The direct transfer from millimetre waves to light waves makes our modulator particularly versatile regarding the frequency and exact format of data encoding", Leuthold emphasizes.

In fact, the modulator is already compatible both with the new 5G technology and with future industry standards based on millimetre-wave and terahertz frequencies of 300 Gigahertz and data transmission rates of up to 100 Gigabits per second. Moreover, it can be produced using conventional silicon technology, and thus at a comparatively low cost.

Finally, Leuthold can reassure users who might be worried about the electromagnetic radiation involved. Differently from the radio waves or microwaves of a WiFi modem, which propagate evenly in all directions, millimetre waves can be strongly focused for transmission to the outside and only propagate between the roof antenna and a light pole inside a beam that is twenty centimetres in diameter. This strongly reduces the power needed for transmission compared to other wireless technologies. It also eliminates the typical problems of WiFi modems, whose signals can get in each other's way.

###

Reference

Salamin Y et al.: Microwave plasmonic mixer in a transparent fibre-wireless link, Nature Photonics, 29 October 2018, doi: 10.1038/s41566-018-0281-6 [http://dx.doi.org/10.1038/s41566-018-0281-6]

Media Contact

Prof. Dr. Jürg Leuthold
leuthold@ethz.ch
41-446-338-010

 @ETH_en

http://www.ethz.ch/index_EN 

Prof. Dr. Jürg Leuthold | EurekAlert!
Further information:
https://www.ethz.ch/en/news-and-events/eth-news/news/2018/11/millimetre-waves-for-the-last-mile.html
http://dx.doi.org/10.1038/s41566-018-0281-6

More articles from Information Technology:

nachricht NIST's antenna evaluation method could help boost 5G network capacity and cut costs
11.12.2018 | National Institute of Standards and Technology (NIST)

nachricht ETRI exchanged quantum information on daylight in a free-space quantum key distribution
10.12.2018 | National Research Council of Science & Technology

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

Im Focus: Three components on one chip

Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.

Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...

Im Focus: Substitute for rare earth metal oxides

New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals

Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.

Im Focus: A bit of a stretch... material that thickens as it's pulled

Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.

Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

Expert Panel on the Future of HPC in Engineering

03.12.2018 | Event News

 
Latest News

Electronic evidence of non-Fermi liquid behaviors in an iron-based superconductor

11.12.2018 | Physics and Astronomy

Topological material switched off and on for the first time

11.12.2018 | Materials Sciences

NIST's antenna evaluation method could help boost 5G network capacity and cut costs

11.12.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>