Coherent Data Center Links
Jose Krause Perin, Anujit Shastri, Joseph M. Kahn
Abstract
As link bit rates within and between data centers continue to increase, it is challenging to maintain low power consumption while accommodating ever-tighter optical link budgets. Although power consumption can be reduced by co-packaging optical transceivers with electrical switches and employing optical switching, both approaches increase losses, further compressing link budgets. Local oscillator-based coherent receivers traditionally employed for long-haul systems provide a path to higher bit rates and improved link budgets, but their power consumption is excessive owing to high-speed digital signal processing (DSP). We discuss alternative designs for coherent receivers, such as DSP-free coherent receivers and Kramers–Kronig (KK) receivers. We compare them in terms of receiver sensitivity, power consumption, and complexity.