All-ETDM 107-Gbaud (214-Gb/s) Single-Polarization QPSK Transmitter and Coherent Receiver

We demonstrate an all-electronically multiplexed, single-polarization 107-Gbaud quadraturephase-shift-keyed (QPSK) transmitter and off-line coherent detection using a real-time sampling oscilloscope prototype with 63-GHz electronic bandwidth, sampled at 160-GS/s. Using only distributed feedback lasers, we obtain a back-to-back implementation penalty of 4 dB and 2400-km transmission. . Introduction Symbol rates up to 107 Gb/s using electronically multiplexed transmitters and receivers have been previously demonstrated in direct detection experiments using on/off keyed (OOK), duobinary and differential phase shift keyed (DPSK) modulation formats [1,2], enabled by high speed electronic multiplexers, photodiodes, and demultiplexers [3,4]. With the move to digital coherent detection in optical transport [5], symbol rates have been limited by the bandwidth of analog-to-digital converters (ADCs), which in off-line research experiments take the form of fast sampling oscilloscopes; the highest symbol rates reported for coherent detection today is 80 Gbaud [6]. Optical techniques have been employed to circumvent this limitation and quasi-real-time sampling of a QPSK signal has been demonstrated at 66 [7]. Here we demonstrate the first coherent reception of a 107-Gbaud (214-Gb/s) singlepolarization QPSK optical signal using a realtime sampling oscilloscope operating at 160Gs/s with a 63-GHz electrical bandwidth. Owing to the relaxed phase noise requirements at the high symbol rate, we use distributed feedback lasers (DFBs) for both signal and local oscillator (LO).