Dutch-sponsored researcher Christos Tsekrekos has investigated how a small network for at home or in a company can function optimally. His research analyses the MGDM technique (Mode Group Diversity Multiplexing) of the Eindhoven University of Technology.
This technique transmits each TV, telephone and Internet signal via a separate group of light rays through the optical fibre cable. Such a technology has not yet been marketed. Yet in the ideal situation it could be applied in a glass or polymer fibre, has the potential of being cheap, and transmits all information without disruption.
Existing systems for small networks at home or in a company make use of multimode glass fibres or multimode polymer optical fibres (POF). The latter are relatively thick cables (about 1 mm thick, thus thicker than the glass fibre which is 0.125 um thick). Multimode fibre cables can conduct many light rays and can operate free of disruption and with a greater bandwidth than a wireless connection. However, due to a slight variation in the speed of the light rays through the multimode fibre, a signal transmitted by all of these rays becomes spread out. Consequently, the signals become broader and therefore fewer signals fit in the fibre, limiting the transmission capacity.
Independent channels
Tsekrekos investigated how the MGDM technique can increase the capacity of a multimode fibre network. He created independent channels by dividing the total group of light rays into groups of closely related light rays (or modes). Using special optical and electrical techniques, Tsekrekos investigated how the crosstalk between these groups could be eliminated so as to render these groups independent of each other.
This step allows several groups to be used in parallel, thereby increasing the fibre's capacity. Moreover, each group can transport its own type of signal, which means that TV, telephone and Internet signals can be transmitted though the same fibre.
Using this approach the researcher constructed a simple yet stable MGDM system. The system works well up to distances of 1 km of multimode glass fibre with a core diameter of 62.5 um. Tsekrekos invented a new mode-selective spatial filter (MSSF), based on lenses with specific characteristics, to make the system reliable and to allow a large number of channels to be realised. This can result in a stable and transparent five-channel MGDM system.
Philips, Draka Fibre, TNO-ICT, and several electrical contractors are supervising this project in the Technology Foundation STW users' committee. Philips and TNO-ICT are very interested in home networks that can flexibly transport a wide range of signals.
The MGDM technology together with thick multimode glass or polymer fibres will soon make it possible for consumers to simply install a universal and high capacity broadband network at home. Draka Fibre (in Eindhoven) considers the MGDM technology to be a highly promising means of obtaining even more capacity and possible applications out of this type of fibre. Further research should lead to a greater increase of the multiplex factors in more complex network structures.
Source: NWO
Related stories:
Discovery of a new way to manipulate light a million times more efficiently
A discovery of a new way to manipulate light a million times more efficiently than before is announced in the journal
Science this week.
Bones at the nanoscale
Scientists from Max Planck Institute (Germany) and the European Synchrotron Radiation Facility have just discovered the way deformation at the nanoscale takes place in a bone by studying it with the synchrotron X-rays. This study explains the enor-mous stability and deformability of bones. The hierarchical structure of bones makes them able to sustain large strains without breaking, de-spite being made of essentially rigid units at the molecular level. The re-sults are published this week in the
PNAS online edition.
Paint-on semiconductor outperforms chips
Researchers at the University of Toronto have created a semiconductor device that outperforms today's conventional chips -- and they made it simply by painting a liquid onto a piece of glass. The finding, which represents the first time a so-called "wet" semiconductor device has bested traditional, more costly grown-crystal semiconductor devices, is reported in the July 13 issue of the journal
Nature.
World record 10.4 Gigabit wireless transmission
Researchers at the University of Essex are claiming a world record for the amount of computer data sent over a point-to-point wireless channel.
The results achieved by the team from the Department of Electronic Systems Engineering are the equivalent of more than 162,000 phone calls or over 10,000 broadband internet connections being made simultaneously. Such large capacity could revolutionise wireless internet download times for many households and local businesses, small and large.
Light's Answer To Ultrasound
You have a tiny wound on your hand that doesn’t heal, a bad burn on your chest – or an injured retina. Your doctor cannot tell how serious the injuries are below the surface. He needs tissue samples. That means using a scalpel, which again equals pain, perhaps even a risk. Soon there may be hope for an improved and totally harmless method to peer under the surface of the skin: light.
Nanotechnologists' new plastic can see in the dark
Imagine a home with "smart" walls responsive to the environment in the room, a digital camera sensitive enough to work in the dark, or clothing with the capacity to turn the sun's power into electrical energy. Researchers at the University of Toronto have invented an infrared-sensitive material that could shortly turn these possibilities into realities.
In a paper to be published on the
Nature Materials website Jan. 9, senior author Professor Ted Sargent, Nortel Networks – Canada Research Chair in Emerging Technologies at U of T's Department of Electrical and Computer Engineering, and his team report on their achievement in tailoring matter to harvest the sun's invisible rays.
World first: Lasers used in keyhole surgery for brain cancer
In a ground-breaking advance, French neurosurgeons on Friday said they had successfully treated brain tumours through ultra-keyhole surgery, using a tiny fibre-optic laser to destroy cancerous cells.
Sesame seed extract and konjac gum may help ward off Salmonella and E. coli
A new study in SCI's
Journal of the Science of Food and Agriculture shows that konjac gum and sesame seed extract may offer protection against different strains of E. coli and Salmonella bacteria.