Enhanced-Performance Tunable Sources for Fast AWGR-Based Optical Switching Data Center Networks

Optical switching based on arrayed waveguide grating routers (AWGRs) and fast tunable sources is a future-proof solution to overcome the bottleneck of limited bandwidth and high latency of electrical switches-based data center networks (DCNs). To support fine-grained optical packet switching and maintain high network throughputs, tunable sources capable of nanosecond-scale hitless wavelength switching are critical requirements for such fast optically switching networks. In this work, we experimentally demonstrate a fast-tunable source based on a high-density multi-wavelength DFB laser array monolithically integrated with a three-stage Y-branch combiner and an SOA. The DFB laser array has an average 100-GHz channel spacing under the same bias current. The output power of all lasers is above 10 mW, with a uniformity of less than 1 dB. Benefitting from the high-speed dynamic property of the DFB laser and high-speed burst drive pulses controlled by a field-programmable gate array (FPGA), less than 3 ns switching time is achieved by the on-off switching of the DFB laser on arrays, which is independent of tuning range. Furthermore, a 2 × 2 optical switching prototype based on this demonstrated chip and AWGRs achieves error-free transmission atop 25 Gbps NRZ per link with 12.8 ns end-to-end reconfiguration, which provides a path toward a high-bandwidth, low-latency, and energy-efficient wavelength-switched network for data centers in the post-Moore's Law era.