Has the Time Come for Coherent Optics in Access Networks? 

Thursday, 10 March 08:00 – 10:00


Naveena Genay, Orange Labs Network, France
Dora van Veen, Nokia Corp., USA
Mu Xu, CableLabs, USA


Coherent optical communication is a game-changer technology for high-speed data transmissions in long-haul networks and data center interconnects, enabling a widespread upgrade and new deployment of optical transport networks to speeds of 100 Gbps, 200 Gbps, and 400 Gbps per wavelength. Recently, the potential of using coherent optics in access networks incurs a lot of discussions in both industry and academia. Following the continuation of growing bandwidth demands in ultra-high-definition video streaming, cloud computing, immersive gaming, 5G, VR, and remote healthcare, we are pushing really hard on conventional intensity-modulation direct-detection (IMDD) systems and approaching their performance limit. On the other hand, with the progress of silicon photonics, semiconductor fabrication process, and new form factor, the cost of coherent systems continues to reduce, which may enable coherent optics to partly replace direct-detection links in mobile xHaul, edge networks, and fiber to the home (FTTH) in high density communities. It is anticipated that, with the greatly improved receiver sensitivity and stronger robustness under chromatic dispersion, coherent optics could significantly enhance the number of connected users and transmission distance for next-generation passive optical networks (PONs). The legacy ODN (Optical Distribution Network) deployed based on previous generations of PONs such as GPON, XG(S)-PON and recently the 50G-PON currently undergoing standardization has optical budget as high as 32 dB. With emerging higher data rates, operators need to capitalize on legacy ODN, whether by migration or coexistence with already deployed PON systems, with the challenge of meeting the high budget constraints. Hence at 100Gbit/s per wavelength, coherent systems could address the high optical budget as well as the penalties due to dispersion which are inherent to IMDD. On the other hand, using coherent optics in access networks faces a lot of challenges making IMDD still a very competitive and reliable low-cost solution. It may require significant changes in today’s PON architecture, PHY, and MAC layers to introduce coherent PON. A great number of technical issues await to be resolved. The increased cost is also a major concern, which requires strategic cost-per-bit analysis for future network evolution.

So, as an effort for pioneering future explorations, in this panel, discussions are anticipated to address some of the following key questions. Will coherent optics be an answer for access networks? What will be the target bandwidth for next-generation PON? What are the roles of coherent optics and IMDD in future broadband access? Wat about WDM-PON? What are the driven forces and bottlenecks? What are the differences of using coherent optics in metro vs access and can these differences lead to simplified design or DSP to bring down the cost? Any new solutions to control the cost?

Topics may include, but will not be limited to:

  • Comparison of coherent optics vs IMDD in technical and marketing perspectives
  • Cost per bit analysis of coherent optics and IMDD
  • Architecture and system design for coherent optical access
  • Adaptation and optimization of coherent optics for access networks
  • Simplified coherent transmitter and receiver
  • New IMDD technologies to maintain its competitiveness
  • Coexistence of IMDD and coherent optics
  • Cost reduction of coherent optical systems
  • Integrated photonics and packaging technology for coherent systems
  • Low-complexity DSP for coherent access
  • The role of IMDD WDM-PON


Ed Harstead, Nokia, USA
Progress and Limits of IM-DD PON, and Directions for Coherent PON

Zhensheng Jia, CableLabs, USA
Coherent Optical Technology and Novel Architectures for Access Networks

Argishti Melikyan, II-VI Optical Systems, USA
Enablers for Cost-effective Coherent Optical Access and Data Center Transceivers

Albert Rafel, British Telecom, United Kingdom
Operator View on Coherent Access with Respect to Use Cases, Requirements, and Cost

Seb Savory, University of Cambridge, United Kingdom
What are the Limitations and Advantages of Using IM-DD and Coherent Detection in Optical Access Networks?

Antonio Teixeira, Sr., University of Aveiro, Portugal
Novel Architectures in Next-gen Optical Access Networks: TDM Versus WDM / P2P Fiber; and Single Carrier versus Multi Carrier (XR-optics, UDWDM, etc)