Four-Channel 100-Gb/s per Channel Discrete Multi-Tone Modulation Using Silicon Photonic Integrated Circuits

The emerging communication applications for inter- and intra- data centers demand low-cost and small-from-factor optical transceivers with 100G/400G capacity. Various techniques, such as wavelength-division multiplexing (WDM), multi-level pulse-amplitude modulation (PAM), and discrete multi-tone (DMT), are heavily investigated in this field. Among these techniques, DMT can offer 100-G capacity with 10-20G optical devices, which provides a very promising low-cost 100G/400G solution. In this paper, we report four-channel DMT using silicon photonic circuits with net channel rates of 100 Gb/s and 70 Gb/s detected by commercial and integrated germanium receivers, respectively. The silicon photonic chip integrates four silicon Mach-Zehnder modulators (MZMs) and WDM multiplexers based on thermally tunable second-order microring filters. Besides the wavelength multiplexing functionality, we also demonstrate that these microrings can serve as vestigial sideband (VSB) filters to enhance the transmission performance in 20-40 kilometer ranges. These demonstrations indicate the promise of using low-cost and high-integrated silicon photonic circuits to fulfill high capacity 100G/400G applications.