Global Sources
EE Times-India
Stay in touch with EE Times India
EE Times-India > Networks

New transmitter significantly boosts optical fibre capacity

Posted: 11 Dec 2013     Print Version  Bookmark and Share

Keywords:EPFL  optical fibre  Nyquist sinc pulse  transmitter 

A team of researchers at Ecole Polytechnique Federale de Lausanne, Switzerland (EPFL) has discovered a way to increase fibre optic capacity in existing networks by 10 times just by switching to a new kind of transmitter. Using sinc-shaped Nyquist pulses, information can be encoded on pulses that overlap in the time domain and use a minimum of spectral bandwidth, thus maximizing optical capacity.

Other groups have tried to produce Nyquist sinc pulses to minimize inter-symbol interference, but had to resort to complex signal generators. Camille Bres and Luc Thevenaz claim their spectral synthesis technique works better, plus is the only one that will be easy to implement for commercial optical transmitters.

"We synthesize a spectrum that gives the perfect pulse shape. We do it by using a simple intensity modulator to generate a set of spectral lines, regularly spaced and showing exactly the same amplitude and the same phase. This gives automatically in the time domain the sinc pulse shape," Thevenaz said. "This is very simple and straightforward, but nobody thought to do it this way before."

New transmitter significantly boosts optical fibre capacity

Figure 1: Artists conception of Nyquist pulses encoding 10-times more information. Source: Jamani Caillet/EPFL

The EPFL team claims that in the lab a laser and a modulator, to produce wide-spectrum pulses, are all that's needed to generate Nyquist pulses that are 99 percent perfect.

The researchers claim that designing a transmitter chip that realizes their encoding technique should be a straightforward exercise for optical chipmakers, and would include "the modulators required to generate the square shaped spectrum and a set of short delay lines and modulators to generate data sequences and to interleave them in the temporal sequence, to increase the data rate," said Thevenaz.

The spectral synthesis technique, which produces a rectangular-shaped, phase-locked frequency comb, could also be useful in other fields, according to the researchers, including microwave photonics, light storage and all-optical sampling.

- R. Colin Johnson
  EE Times

Comment on "New transmitter significantly boosts..."
*  You can enter [0] more charecters.
*Verify code:


Visit Asia Webinars to learn about the latest in technology and get practical design tips.


Go to top             Connect on Facebook      Follow us on Twitter      Follow us on Orkut

Back to Top