Development of new transition method for beyond the 5G era: signal-to-noise ratio is improved nine-fold after optical signal transmission

On July 26, KDDI Research Inc. announced that it had invented and successfully demonstrated a novel transmission method based on the four-wave mixing phenomenon that occurs in an optical fiber to improve the optical signal component (SN ratio) input to the optical fiber, by nine times after transmission.

In existing transmission methods, the SN ratio is not increased after transmission, and is either the same as before transmission or is decreased owing to signal degradation. In contrast, the novel method can significantly improve the SN ratio after transmission and can increase the transmission capacity by approximately three times in comparison with that in conventional transmission methods, for example, when switching from a QPSK signal to a 64QAM signal.

According to the company, this is a revolutionary technology that is expected to serve as the basis for expanding the transmission capacity of optical fiber communication in the future to support Beyond 5G/6G networks. In the Beyond 5G/6G era, a considerably larger amount of data is expected to flow through networks than that currently flowing. Therefore, an optical fiber communication network is required to sufficiently expand the capacity for accommodating data (transmission capacity and transmission distance).

As a result of this technology, the capability of optical fiber communication networks can be enhanced by overlaying more information on a single optical signal. However, the optical signal component needs to be expanded by the amount of superimposed information, and if it cannot be made sufficiently large, the transmission distance needs to be reduced. Due to this, there is a need to develop a transmission method capable of significantly increasing the optical signal component after optical fiber transmission.

KDDI Research Inc. invented a transmission technology that improves the optical signal component input to the optical fiber by nine times after transmission by utilizing a non-linear optical effect known as four-wave mixing (FWM), wherein two different frequencies are generated from each of two light waves, resulting in a total of four light waves. The company has confirmed that the optical signals used in this new technology are expected to be used in the Beyond 5G/6G era, and that the optical signal components have been improved by approximately nine times.

These findings were presented as a post-deadline article in which the most recent achievements are carefully selected and presented at Optical Communication Conference & Exposition 2021 (OFC2021), the world's largest international academic conference in the field of optical communication.