Researchers at MIPT, together with Corning engineers, created a system for transmitting a high-speed signal over long distances without active intermediate amplification. The results are published in the journal IEEE Photonics Technology Letters.
To transmit information in countries with large uninhabited spaces, the construction of intermediate signal amplification stations is required, otherwise it simply will not reach its destination. To reduce the cost of communication over long distances, fiber-optic systems are invented that can transmit a signal without amplification along the way. Now there are systems that can connect stations at a distance of up to 500 km with a speed of up to 100 Gb / s.
The authors of the work in question managed to transmit a signal over a distance of 520 km at a speed of 200 Gb / s. Previously, such a ratio of speed and range was achieved only in scientific laboratories, but the results were not applicable outside of them. This time, Corning's commercially available cables were used for transmission. This makes the transmission technology applicable in the field. So that the signal does not fade, it was amplified at the very beginning and remotely at two intermediate points.
“To amplify a signal in a passive fiber, high-frequency radiation of high power propagated along with it. Such an approach allowed us to significantly improve the ratio of signal power and noise at the output of the line, ”explains Dmitry Starykh, one of the authors of the work, a graduate student at the Physics and Technology School of Radio Engineering and Computer Technology at MIPT.
The cable was divided into 3 sections, each of which consisted of 2 types of wires connected in series. Also, at the junction of the sections, receivers for remote optical pumping were installed. Using laser radiation, electromagnetic waves were transmitted to these receivers that amplified the signal. The connection points of the sections were selected for the most optimal signal amplification. The first receiver stood 122 km from the transmitter, and the second 130 km from the receiver. In their work, the researchers chose a signal change frequency that is optimal in terms of signal-to-noise ratio - 57 billion times per second. Although the system used allows signal transmission at speeds up to 400 Gb / s, engineers reduced it to 200 Gb / s to increase the range.
Today, work is already underway to create a fiber optic system with increased maximum speed. If now the upper speed limit is about 400 Gb / s, then in the developed system it is planned to achieve a speed of 600 Gb / s per channel.