Siemens shows 1Gbit/s over plastic fibre

Siemens researchers have demonstrated a data rate of 1Gbit/s over plastic optical fibre, a speed ten times higher than is possible with current products.

Sebastian Randel, the Siemens project manager, said the team sent an IPTV signal at 1008Mbit/s over a 100m connection in the lab, without errors or any flickering on the TV screen.

The company claims this is a big breakthrough for plastic (or polymer) optical fibre - POF - a technology which proponents want to supplant glass fibres and copper wires in demanding environments such as factory and home automation.

POF's advantages include flexibility, robustness and ease of connection, all of which make it easier and therefore cheaper to handle - it can even be installed by us cack-handed end users. In particular, the optical core is much thicker than in glass fibre, so it is more tolerant of misaligned connectors, and it can be cut satisfactorily with a metal cutter, whereas glass needs a diamond cutter.

Its main disadvantage is that it has a much higher transmission loss than glass, so current POF technology tops out at 100Mbit/s - the speed of Fast Ethernet.

What the Siemens team has done is to use a different modulation scheme - in fact, it's quadrature amplitude modulation, as used in DSL and the latest Wi-Fi specs. Instead of simple binary, QAM has 256 signal states so each pulse can carry far more information, hence the ten-fold speed increase.

Its robustness means that POF cable is already used is some demanding areas, such as inside cars and high-speed trains, and of course in lighting. It is used in audio too, with connections based on the IEEE 1394 Firewire spec - like glass fibre, it is immune to electrical interference and doesn't generate noise or crosstalk.

Randel suggested that taking it to Gigabit speeds could also make it suitable for applications such as factory and medical networking, and for home LANs to support high-def IPTV.

He added though that this was just a demonstration, and said he could not quote dates or prices for possible Gigabit plastic optical fibre products.