Proof of Concept of Polarization-Multiplexed PAM Using a Compact Si-Ph Device

We experimentally propose and demonstrate how to double the capacity per wavelength in short distance data center interconnect fiber links by polarization multiplexing two pulse-amplitude modulation streams and by using a very compact silicon photonic polarization rotator driven by an algorithm implemented in a low-speed digital signal processing platform, avoiding more complex coherent and/or Stokes receiver structures. Tackling up to 100 rad/s, the system gives automatic stabilization against polarization fluctuations. We also report on the experimentally measured evolution of the state of polarization in an installed data center link.