A new laser that can make Internet faster

We won't, hopefully, have to fret over the slow data transmission soon.

A new laser developed by a research group at the California Institute of Technology (Caltech) holds the potential to increase the rate of data transmission in the optical-fibre network.

The optical-fibre is the backbone of the Internet.

"Light is capable of carrying vast amounts of information. But to utilise this potential, the laser light needs to be as spectrally pure (close to a single frequency) as possible," explained post-doctoral scholar Christos Santis and graduate student Scott Steger who led the project.

The purer the tone, the more information it can carry.

Today's worldwide optical-fibre network is still powered by a laser known as the distributed-feedback semiconductor (S-DFB) laser, developed in the mid 1970s.

Originally, laser beams in optic fibres carried information in pulses of light; data signals were impressed on the beam by rapidly turning the laser on and off, and the resulting light pulses were carried through the optic fibres.

However, to meet the increasing demand for bandwidth, communications system engineers are now adopting a new method of impressing the data on laser beams that no longer requires this "on-off" technique.

This method is called coherent phase communication.

The digital electronic bits carrying video, data, or other information are converted at the laser into these small delays in the otherwise rock-steady light wave.

But the number of possible delays, and thus the data-carrying capacity of the channel, is fundamentally limited by the degree of spectral purity of the laser beam.

The findings were published in the journal Proceedings of the National Academy of Sciences.

This purity can never be absolute, but with the new laser, Yariv and his team have tried to come as close to absolute purity as is possible.

--Indo-Asian New Service

mak/na/rd