Generation and 1200-km Transmission of 448-Gb/s ETDM 56-Gbaud PDM 16-QAM using a Single I/Q Modulator

We generate 56-Gbaud PDM 16-QAM using electronic time-division multiplexing (ETDM) and a four-level-driven I/Q modulator. The 448-Gb/s line-rate signal is coherently received using two 32-GHz oscilloscopes with >5.5 effective bits, and is transmitted over 1200 km of ultra-large-area fiber. Introduction With the recent commercialization of 100-Gb/s transport technologies, research is focusing on scaling per-channel bit rates beyond 100 Gb/s, with the goal to develop spectrally efficient opti1 cal interfaces for the next Ethernet standards , likely at 400 Gb/s and 1 Tb/s. Approaches include electronic and/or optical orthogonal sub2 carrier multiplexing and single-carrier multilevel 3-6 modulation at high symbol rates . The latter method allows for a simpler transmitter structure at approximately equal receiver and digital 7 signal processing hardware . Using electronic time-division multiplexing (ETDM) at both transmitter and receiver, single-carrier systems with polarization-division multiplexing (PDM) have 8,9 demonstrated up to 240 Gb/s, using direct or 4 coherent detection and complex modulator structures. Using a single quadrature (I/Q) modulator, per-channel bit rates of up to 224 Gb/s have been demonstrated, both with 28Gbaud 16-ary quadrature amplitude modu5,6 lation (16-QAM) and with 56-Gbaud quadra3 ture phase shift keying (QPSK). All these feature per-polarization ETDM bit rates of ~100 Gb/s (cf. Fig. 1). By resorting to optical time division multiplexing (OTDM) at the transmitter, 10 456 Gb/s has been achieved with PDM 16QAM, and the use of complex OTDM techniques at both transmitter and receiver has enabled bit 11,12 5.1 Tb/s.