Design considerations for a 33mW, 12.5 Gbps × 8 channel silicon photonic transmitter array

We report on a hybrid assembly combining 40 nm bulk CMOS transmitter circuits, 130 nm SOI optical ring modulators, and off-chip lasers. Silicon resistors in the rings enable circuit-based thermal tuning to overcome process variations, resulting in eight 12.6 Gbps channels operating simultaneously at eight different wavelengths. Not counting laser power but including all transmitter circuits, integration parasitics, and static thermal control, the TX array consumes a total of 33 mW, resulting in a net per-channel efficiency of 330 fJ/b.