High-Speed Bi-Directional Transmission Over Multimode Fiber Link in IM/DD Systems

We demonstrate a 14.5-Tb/s bi-directional transmission over 2.2 km of OM2 fiber using the selective excitation of four mode groups based on multiplane light conversion technology, wavelength division multiplexing, and direct detection. Forty wavelengths per mode group are used; each wavelength is modulated with a discrete multitone scheme with a fast Fourier transform length of 1024 subcarriers. An 88-Gs/s digital-to-analog converter is used to drive an external lithium niobate Mach-Zehnder modulator. The impact of each component in the line is studied experimentally. Moreover, Chow's rate-adaptive algorithm for bit and power allocation is optimized and adapted to the region where the bit error rate (BER) increases. In this paper, we are considering a hard-decision forward error correction (FEC) limit corresponding to a BER of 5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> and assume a 7% overhead. To the best of our knowledge, the achieved bitrate in this paper is the highest throughput transmitted over multimode fibers using direct detection.