Coherent optical interconnects using Fermat number transform and hollow core fibre.

With the exponential growth of artificial intelligence-driven data centre traffic, next-generation data centre optical interconnects must deliver high-speed data transmission while ensuring low latency and power consumption. Here, we present an ultra-simple low-latency self-homodyne coherent interconnect solution through anti-resonant hollow core fibre and leverages the Fermat number transform to implement the entire digital signal processing. The Fermat number transform eliminates the round-off errors prevalent in the fast Fourier transform through modulo operations and replaces computationally intensive multiplications with simple cyclic shift and addition operations. As a proof of concept, we demonstrate bidirectional transmission through a 5.1-km anti-resonant hollow core fibre, achieving a data rate of 448 Gb·s^-1. Our proposed scheme reduces complexity of digital signal processing by 90%, whereas the integration of the anti-resonant hollow core fibre reduces the propagation latency by 28.4%. This work establishes a promising path to push the energy-efficiency boundary of coherent structure and enables large scale deployment of coherent optical interconnects.