[Laser] Japanese researchers transmit 3Gbps using far infrared

[bernieS]

Apparently 300cm is DX in this mode ;-)

-bernieS


http://www.extremetech.com/extreme/129447-japanese-researchers-develop-3gbps-wifi-for-terahertz-frequencies

Japanese researchers transmit 3Gbps using terahertz frequencies

By Neal Gompa on May 16, 2012 at 1:02 pm

Researchers at the Tokyo Institute of Technology have developed a new 
wireless transmission system that works above all currently regulated 
spectrum frequencies. The new system works at the range of 300GHz to 
3THz (terahertz), which is the Far Infrared (FIR) frequencies of the 
infrared spectrum. That spectrum is currently totally unregulated by 
any country or standards organization in the world, making it ripe 
for development of new technologies. So far the Japanese researchers 
have transmitted data at 3Gbps, but in theory speeds of up to 100Gbps 
should be possible.

The new "T-ray" wireless transmission system is similar to WiGig in 
that it requires line of sight and can transmit large amounts of data 
at once. However, WiGig runs at "just" 60GHz, meaning it can actually 
work with distances larger than a couple of meters without 
significant power boosting. This T-ray system will be limited to 1-3 
meters without significant power boosting. With power boosting, it 
could match or surpass WiGig in range.

What made this research possible was the development of a small 
transceiver for FIR frequencies that is a small as a one-yen coin and 
affordable for mass production. Back in November, a Japanese 
semiconductor research and production company by the name of Rohm 
developed one and estimated that it would be ready for commercial 
production within three to four years.

T-rays will likely be used for server farms before anything else, 
because its high throughput and low latency (due to lack of 
electromagnetic interference at FIR frequencies) will be a boon to 
those who want to reduce the amount of complex wiring required to 
connect the large swaths of servers together. T-rays are also used 
extensively in medical and security imaging, because they penetrate a 
few millimeters of skin. Any other uses (such as T-ray WiFi) will 
come later after the cost of producing the radios fall.


Also...


http://www.bbc.co.uk/news/science-environment-18072618

16 May 2012 Last updated at 03:00 ET

Milestone for wi-fi with 'T-rays'

Researchers in Japan have smashed the record for wireless data 
transmission in the terahertz band, an uncharted part of the 
electro-magnetic spectrum.

The data rate is 20 times higher than the best commonly used wi-fi standard.

As consumers become ever more hungry for high data rates, standard 
lower-frequency bands have become crowded.

The research, published in Electronics Letters, adds to the idea that 
this "T-ray" band could offer huge swathes of bandwidth for data transmission.

The band lies between the microwave and far-infrared regions of the 
spectrum, and is currently completely unregulated by 
telecommunications agencies.

Despite the name, the band informally makes use of frequencies from 
about 300 gigahertz (300GHz or about 60 times higher than the current 
highest wi-fi standard) to about 3THz, 10 times higher again.

It is used principally for imaging in research contexts, as terahertz 
waves penetrate many materials as effectively as X-rays but deposit 
far less energy and therefore cause less damage.

Until recently, the technology required both to generate and detect 
these "T-rays" has been too bulky, costly or power-hungry to offer a 
plausible alternative to existing devices tucked within smartphones 
or wi-fi routers.

That looks set to change; in November electronic component firm ROHM 
demonstrated a 1.5Gb/s (1.5 billion bits per second) transfer rate at 
a frequency of 300GHz.

Terahertz wi-fi would probably only work over ranges of about 10m, 
but could in theory support data rates up to 100Gb/s - close to 15 
times higher than the next-generation 802.11ac wi-fi standard that is 
under development.

The new work, by researchers from the Tokyo Institute of Technology, 
demonstrated 3Gb/s transmission at 542GHz.

At the heart of the team's 1mm-square device is what is known as a 
resonant tunnelling diode, or RTD.

Tunnelling diodes have the unusual characteristic that the voltage 
across them can sometimes go down as current is increased.

RTDs are designed such that this process makes the diode "resonate", 
which in the current work's design means it sprays out waves in the 
terahertz band.

The team is now working to improve their proof-of-principle device 
and extend its range deeper into the terahertz regime, as well as 
increasing its power output.