First Demonstration of an O-Band Coherent Link for Intra-Data Center Applications

We report the first demonstration of a full O-band coherent link for intra-data center applications, including custom photonic and electronic integrated circuits for the transmitter and receiver. Full-link 112 Gbps (56 Gbaud QPSK) transmission is shown with <inline-formula><tex-math notation="LaTeX">$2.1\cdot 10^{-4}$</tex-math></inline-formula> measured BER, and record baud rate 128 Gbps (64 Gbaud QPSK) transmission is shown for the stand-alone coherent transmitter. The link architecture is based on analog coherent detection (ACD), which improves power consumption substantially by performing functions in the analog domain that are normally implemented with power-hungry digital signal processing (DSP). Energy efficiency of 9.5 pJ/bit is demonstrated for the O-band coherent link, with 12.5 pJ/bit expected with next-generation circuits that include integrated optical gain. These results show the potential for next-generation data center networks based on low-power O-band coherent links.