Recent co-packaged Si-Ph based optical transceivers for HPC interconnects

Silicon photonics (Si-Ph) based optical interconnects (I/O) are expected to provide the escape bandwidth needed for high performance computing (HPC) platforms. Current highvolume products for optical I/O are in the form of pluggable modules composed of discrete electronics and photonics ICs that plug into server racks. These modules can be limited in energy efficiency due to the relatively long (inches-long) high-speed electrical interconnect between the pluggable module and the XPU. Recent advances in ultra-compact Si-Ph optical modulators, multi-wavelength lasers, and a migration of the interface electronics to densely-integrated silicon processes, have resulted in compact optical I/O modules. Nearpackaged optics (NPO), or collocating the optical I/O on the same package as the compute node (co-packaged optics or CPO) allows implementing energy-efficient signaling in the optical transceiver. In this talk, I will present an introduction to models of photonic building blocks for wireline circuit designers and review recent industry work on intensity-modulated optical transcievers including work on dramatically scaling optical I/O data-rates at isoenergy efficiency through the use of techniques such as dense wavelength division multiplexing (DWDM) and polarization-division multiplexing (PDM).