Silicon nanowires restore optical signals

A system for reconstructing weak or damaged optical data using tiny silicon waveguides could be incorporated into future optical chips for use in world wide communications networks.

The ability to regenerate weak and distorted optical data is vital for maximizing the performance and transmission span of modern communication systems. Unfortunately, present regenerators have to convert the optical data into electronic signals, process it and then convert it back into the optical domain for re-transmission - a costly and inconvenient approach.

Alexander Gaeta and co-workers have developed an all-optical scheme that can perform complete regeneration (amplification, retiming and reshaping of optical data bits) using silicon waveguides that have nanoscale dimensions. The team used a well-known technique in nonlinear optics called ‘four-wave mixing’ to transfer noisy and degraded data bits from an incoming light beam and convert them into high-quality, clean data bits carried on a second light beam of a different wavelength. The beauty of the approach is that it does not require any electronic circuitry and its tiny size and silicon composition potentially allow integration into optical chips of the future.

The team’s experiments took place at a wavelength of 1,550 nanometres - the region at which the world’s optical networks operate. The next challenge is to make the scheme compatible with multichannel networks that transmit many simultaneous signals, each on its own dedicated wavelength channel.

Author contact:
Alexander Gaeta (Cornell University, Ithaca, NY, USA)
Tel: +1 607 255 9983; E-mail: alg3@cornell.edu