Optical amplifier claims world record low noise performance

Today´s flow of information demands increasing capacity. Optical amplifiers are crucial enablers of data communication, with the mission to increase data signals without first converting them to electrical signals. Not only the speed and capacity require improvements, but it has become increasingly important to maintain a high signal-to-noise ratio of the signal being transmitted.

The researchers at Chalmers University of Technology have used a so-called phase-sensitive fiber-optic parametric amplifier, PSA, to reduce the noise figure to 1 dB. In traditional erbium-doped fiber amplifiers the noise figure is 3 dB at best, resulting in loss of signal integrity. 1 dB is the lowest noise ever reported in any kind of amplifier with reasonably large signal gain. The innovation is implemented in a practical way, making it potentially attractive in various applications – most notably in high capacity optical communication systems.
          
“This is the ultimate optical amplifier. It enables connecting cities, countries and continents more efficiently by placing the amplification hubs at much greater intervals. The signal can also be modulated more effectively. In addition, the amplifier is compatible with any modulation format, with traditional laser transmitters and can be very broadband, making it compatible with many lasers at different wavelengths”, said Professor Peter Andrekson, who has developed the low-noise amplifier together with his research group in fiber optics.
        
The group has taken advantage of the fact that the refractive index of glass is not constant, but dependent on light intensity in the fiber. The new amplifier shows experimentally to have 1 dB noise level, with a theoretical minimum of 0 dB, i.e. no noise being added in the amplification process.
        
“The entire optical telecom industry is our market. But the  technology is generic, and scalable to other wavelengths like visible or infrared light, which makes it attractive in areas such as measurements, spectroscopy, laser radar technology and any applications where detection of very weak levels of light is essential”, said Andrekson.
        
The research is performed at Chalmers University of Technology. It is funded by the European project PHASORS and the Swedish Research Council (VR). Participating partners in the EU project includes University of Southampton, University College Cork, University of Athens, Eblana, OFS, OneFive Photonics and EXFO Sweden AB. The results were published in Nature Photonics.
              
For’ further information: www.chalmers.se.