Transmitting data 16 times faster @ 640 billion bits per second

WASHINGTON - Every second, millions of phone calls and cable TV shows are dispatched through fibres as digital zeros and ones formed by chopping laser pulses into bits.

This slicing and dicing is generally done with an electro-optic modulator, a device for allowing an electric signal to switch a laser beam on and off at high speeds. Reading that fast data stream with a compact and reliable receiver is another matter.

A new error-free speed-reading record using a compact ultra-fast component - 640 gigabites (billion) per second or Gbps - has now been established jointly by scientists from Denmark and Australia.

New technology and new ways of doing business require new approaches to old procedures. Conventional readers of optical data depend on photo-detectors, electronic devices that can operate up to approximately 40 Gbps.

This in itself represents a great feat of rapid reading, but it’s not good enough for the higher-rate data streams being designed now. Sometimes to speed up data transmission several signals are multiplexed: each, with its own stream of coded data, is sent down an optical fibre at the same time.

In other words, 10 parallel streams of data could each be sent at a rate of 10 Gbps and then added up to an effective stream of 100 Gbps. At the receiving end the parallel signals have to be read out in a complementary de-multiplexing process.

Reliable and fast multiplexing and de-multiplexing represent a major bottleneck in linking up the electronic and photonic worlds.

In 1998 researchers in Japan created a data stream as high as 640 Gbps and were able to read it back, but the read-out apparatus relied on long lengths of special optical fibre. This particular approach is somewhat unstable.

The new de-multiplexing device demonstrated at the Technical University of Denmark, by contrast, can handle the high data rate, and can do so in a stable manner.

Furthermore, instead of 50-metre-long fibres, they accomplish their de-multiplexing of the data stream with a waveguide only five cm long, an innovation developed at the Centre for Ultrahigh Bandwidth Devices for Optical Systems, or CUDOS, in Australia.

Another benefit of the new device with the compact size is the potential for integration with other components to create more advanced ultra-fast functional chips. The dynamics involved in the CUDOS device could even allow for still higher data rates approaching terabits/second (Tbps, or trillion bits per second), said a CUDOS release.

Danish scientist Leif K. Oxenløwe, study co-author said that the record speeds of de-multiplexing represented by his tiny glass microchip is a boon to circuit designers and opens the door to faster network speeds. In the near future, the Danish and Australian researchers hope to achieve 1 Tbps Ethernet capability.

These findings were published in Optics Express, the Optical Society’s (OSA) open-access journal.