Single-carrier Vs Multi-carrier For >800G Coherent Optics: A Revived Debate After a Decade


Organizers:

Di Che, Nokia Bell Labs, USA
Hungchang (James) Chien, Marvell Technology Inc., USA
Sander Jansen, ADVA, Germany

Description:

With the advent of coherent detection well over ten years ago, many different modulation formats were investigated to reduce implementation complexity and optimize performance. Multi-carrier modulation formats such as coherent optical OFDM (CO-OFDM) got lots of attention at the time, achieving the first transmission experiment of single-channel 100G and 1T transmission and ultimately leading to the concept of DWDM superchannels. However, the multi-carrier path was not followed by the industry and only single-carrier systems were commercialized at the time. The situation seems to change after a decade. Commercial coherent optics have evolved from 100G to 800G, and a number of industry players have included subcarrier multiplexing (SCM) mode in the latest 800G coherent products.

Will there be a multi-carrier revival? The last workshop at the OFC on multi-carrier modulation formats was back in 2009: “Single-Carrier Versus Multiple-Carrier Modulation Formats for WDM Systems”, so it is about time for an update. This workshop revives the debate from 2009 and address questions like:

  1. Does single-carrier or multi-carrier transmission have any fundamental and unique advantages over its counterpart?
  2. What fundamentally changed in the last 10 years to revive multi-carrier modulation in the latest 800G coherent optics?
  3. Is multi-carrier more difficult than single-carrier to be implemented by real-time DSP? What are the challenges to enable multi-carrier modes for coherent 800G pluggables?
  4. Multi-carrier is known to have better nonlinear tolerance for QPSK by optimizing the symbol rate per subcarrier. Does this scale to modern systems that employ probabilistically-shaped QAM?
  5. As the transceiver symbol rate increases, high-frequency degradation issue with higher symbol rate per transceiver and more cascaded ROADMs. Will adaptive multicarrier formats like bit/entropy loading be essential in those bandwidth-constraint scenarios?
  6.  In the Terabit era, will the single-carrier encounter a bandwidth barrier limited by electronics? Will the optical multi-carrier (superchannel) eventually dominate?

The workshop will combine the historical and the state-of-the-art insights on the controversy, aiming to shed light on the future design of ultrahigh speed coherent optics for the Terabit era.

Speakers:

To be determined.