Two-Channel OTDM System for Data-Center Interconnects: A Review

It has been proposed to implement the >100 Gb/s data-center interconnects using a two-channel optical time-division multiplexed system with multilevel pulse-amplitude modulation. Unlike the conventional four-channel optical time-division multiplexed system which requires an expensive narrow pulse, the two-channel system can be implemented cost-effectively using a wide pulse (which can be simply generated using a single modulator). The two-channel system is expected to be practically available using an integrated transmitter in a chip due to the recent advances in photonics-integrated circuits. This paper reviews the current stage of research on a two-channel optical time-division multiplexed system and discusses possible research directions. Furthermore, it has been demonstrated that 200 Gb/s signals can be generated by using modulators with only 17.2 GHz bandwidth. Therefore, the use of the phase-alternating pulse can make the multiplexed signal robust to chromatic dispersion, enabling the 200 Gb/s 4-level pulse-amplitude-modulated signal to be transmitted over 1.9 km of standard single-mode fiber.

Automated summary

This paper proposes the use of a two-channel optical time-division multiplexed system with multilevel pulse-amplitude modulation to achieve >100 Gb/s data-center interconnects. Unlike the conventional four-channel system, the two-channel system can be implemented cost-effectively using a wide pulse and integrated transmitter. The paper reviews the current research on the two-channel system and discusses future directions, highlighting the ability to transmit 200 Gb/s signals over standard single-mode fiber using phase-alternating pulses.