World record on the single-channel data rate of a standard optical fiber
The fiber-optic communication systems carry 99% of today’s internet traffic. These systems are under pressure due to an exponential rise in the bandwidth-hungry such as video conferencing, HD video streaming and online gaming. In order to increase data-carrying capacity of networks while keeping a lower labor and economic cost, researchers and industries around the world are working hard to achieve higher capacity per fiber.
The innovation is usually applied at transmitters and receivers where information bits are encoded into higher modulation format symbols (i.e. multiple amplitude and phase levels of light), and then, those symbols are transmitted at rates beyond 100 Giga symbol/second. Such systems that are already operating at their limits, distortions from hardware components become critical.
Recently, we studied such a research experimental setup that operates at 128 G symbol/second and can use 16 amplitude levels of light to modulate information. We proposed a NN based nonlinear digital pre-distortion (DPD) filter that compensates the transmitter distortions and improves the signal integrity. By incorporating the responses of actual transmitter hardware in our numerical model and through several numerical simulations, we tailored the architecture of proposed NN-DPD. Furthermore, with our insights of the experimental system the proposed DPD was improved to achieve better performances and to reduce training efforts.
The NN-based filter was tested on the state-of-the-art experiment setup for various degrees of transmitter distortions at Nokia Bell Labs, Stuttgart. With the application of our proposed NN-DPD at transmitter, we compensated the transmitter distortions and achieved a record highest net data rate of 1.61 Tera bits/second over single wavelength. This achievement was presented at Europe’s largest conference on optical communication ECOC 2020 and recognized in Nokia Bell Labs with Bell Labs Summer Intern Award for Outstanding Innovation.