Flexible and Scalable Optical Interconnects for Data Centers: Trends and Challenges

Emerging applications such as machine learning place higher demands on the flexibility and scalability of data center networks. On one hand, it is difficult for the fixed network topology to match the traffic patterns of different neural networks. On the other hand, the rapid growth of training data, model size, and computing requirements has led to an ever-increasing scale of data center networks. Traditional electrical interconnects lack the ability to adjust the network topology and communication bandwidth, resulting in significant resource waste and high expansion costs. Optical interconnects are introduced to solve the above problems because of its high bandwidth, low power consumption, and reconfigurability. In this article, the optical interconnects in recent years are analyzed in detail, and the flexibility and scalability of different networks are compared qualitatively. The future trends and challenges of optical interconnects in data centers are discussed from the aspects of optical transmission technology, optical switching technology, and optical network control and management.