Wide temperature range high-speed VCSEL interconnects using FEC and pre-emphasis

We present PAM-2 and PAM-4 modulated high-speed 850 nm vertical-cavity surface-emitting laser (VCSEL) based interconnects operating across the temperature range -60°C to 140°C. Two different multiple quantum well VCSEL designs were used along with forward error correction, electronic pre-emphasis, and receiver-side equalization techniques. A three-tap feed-forward equalizer was implemented as a pre-emphasis filter, and a least-mean-square equalizer was used at the receiver. We demonstrate successful PAM-4 transmission at 70 Gb/s from -60°C to 100°C, 50 Gb/s at 125°C, and 42 Gb/s at 140°C. The FEC overhead used in the experiments is 3.1%.