25-Gb/s 6.5-pJ/bit 90-nm CMOS-Driven Multimode Optical Link

We report an 850-nm, vertical-cavity surface-emitting laser (VCSEL)-based optical link that achieves new benchmarks in speed and power efficiency. The laser diode driver and receiver ICs are fabricated in standard 90-nm bulk CMOS, and the gallium arsenide optoelectronic devices are commercial components. An operation at a bit-error rate less than 10-12 at 25 Gb/s is achieved, representing the highest speed reported to date for a CMOS-based full optical link. At 22 Gb/s, the link power efficiency is 3.8 pJ/bit and improves further at lower data rates, attaining a minimum of 2.6 pJ/bit at 15 Gb/s. The efficiency numbers reported here, which include a complete accounting of the power dissipation of all the components, are the best reported for any optical interconnect in any technology. This work demonstrates the scalability of VCSEL-based links in both efficiency and speed to meet the demanding requirements of next-generation exa-scale computing and large data center systems.