Optical Circuit Switching Using REC-DFB Laser Array

The ongoing growth of data traffic from existing and new latency-sensitive applications poses a challenge to the data center network. Wavelength-routed optical circuit switching promises high bandwidth, low power and latency networking for data centers, but requires a wideband wavelength tunable source capable of nanosecond-scale hitless wavelength switching at every node. A tunable source based on DFB laser arrays is a potential candidate due to the high-speed dynamic property and high single-longitudinal-mode (SLM) stability of the DFB laser. However, the large-scale integration of the DFB laser and the high precision control of the lasing wavelength are still problems. In this work, we proposed and fabricated a monolithic integrated 16-channel DFB laser array with high SLM stability and 100-GHz channel spacing by using the reconstruction-equivalent-chirp (REC) technique. The maximum output power of each channel was above 6 mW. Based on the custom-designed fast switching drive board with a field-programmable gate array (FPGA), the switch-ON and OFF time between any pair of channel combinations were measured at less than 10 ns. Dynamic switching wavelengths remained stable and resided within the receiver bandwidth. Wavelength switching experiments for modulated light signals were done by driving the external modulator, achieving bit error performance at 1 × 10
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for 10 Gb/s NRZ data.