Scientists from the University of California in San Diego developed a new technology of signaling which use will allow doubling the smallest volumes of information transmitted via fiber-optical communication channels. Introduction of this new technology, the description of which was published in the latest issue of a Science magazine, will enable “to completely change the economy determining the cost of transfer of data flows in modern networks”.
The signals transferring data on an optical fiber in the form of impulses of laser light are rather vulnerable for influence of the optical nonlinear distortions caused by the repeated interaction of the photons of light having various lengths of waves. These nonlinear distortions become a reason why the quality of a signal worsens in the process of its transfer to long distances. And as a solution to this problem, intermediate relaying is used during which optical signals are transformed in electric ones which by means of the computer analysis and digital processing are cleared of any distortions, and then are transformed back to the optical signal transmitted further along the set route.
Such process does not only slow down data transmission, but the cost necessary for this equipment makes the most part of new optical networks development infrastructure cost.
Researchers from the University of California found rather an easy way that enables to get rid of nonlinear distortions. This, in its turn, makes it possible to increase the capacity of optical communication channels in two-four times or to increase the distance which require optical signals before their regeneration and will be able to overcome by the same value.
The problem is that the lasers used in optical communications have rather high stability, but nevertheless radiate light photons whose wavelength differs on the 100-th shares of percent. Such differences in wavelength occur under absolutely casual laws and white noise which they add to a stream of transmitted data, causes nonlinear distortions which are very hard or sometimes cannot simply be filtered.
The method offered by the scientists lies in making uncontrollable changes to the wave lengths of photons of laser light ordered and predictable. In telecommunication technologies some lasers are used which generate light with certain lengths of waves which at the same time extend on optical fiber. The scientists used some methods that transformed an impulse of laser light to the impulse consisting of photons with several fixed various lengths of waves.
The experiments where data were transferred by means of such poly-impulses, showed that the analysis of distortions to which the photons with various lengths of waves passed through an optical fiber of 1000 meters, will allow to precisely define quantitative indices of nonlinear distortions. And this, in its turn, allowed them by means of the simplest methods to completely get rid of distortions, having received an absolutely pure signal at the end.
It is necessary to notice that so far this technology demands rather bulky optical equipment. But, taking into account present development rates of silicon photonics and others areas, adjacent to it, it is possible to expect, that not in such and the far future the technology of transfer developed by the Californian scientists can be miniaturized to that level when it can be used in practice. And this, in turn, will allow to get rid of the need of installation of expensive repeaters of a signal or that is even more important, to increase information transfer speeds on optical fiber in at least twice.