• Technical Conference:  24 – 28 March 2024
  • Exhibition: 26 – 28 March 2024
  • San Diego Convention Center, San Diego, California, USA

Where are the Boundaries Between IM-DD and Coherent?

Sunday, 05 March, 13:00 – 15:30

Room 8

Despite the continuous debate between IM-DD and Coherent, it is an irresistible trend that Coherent has gradually encroached the market share of IM-DD. The extensive deployment of 400ZR over the past few years has marked a big success of Coherent to single-span transmissions like metro/datacenter inter-connects. Currently, academia and industry are actively developing next-generation coherent solutions targeting even shorter distances such as <10km datacenter intra-connects and optical access networks. Besides the advances of DSP/Photonic integration, a hotly pursued pathway to accelerate the expansion of Coherent is Coherent Lite, aiming to simplify or even remove the power-hungry DSP by using lower symbol rate, simpler modulation format, and specially designed analog electronic or optical subsystems.

Though the coherent camp has the ambition to rule the world, the IM-DD camp believes they’ll hold their last stand where the parallel optics solve all the problems and Coherent makes no sense. The question is whether such a stand exists, and if so, where is the eventual boundary between IM-DD and Coherent? The boundary can be characterized by various metrics like data rate, distance, power consumption and transceiver cost, and may be closely related to the application drivers. This workshop will discuss such boundaries and address typical questions like:

  • Will Coherent Lite find its position in the competition between IM-DD and Coherent?
  • Is there a practical technique for an all-analog coherent system to avoid the ADC and DSP?
  • Will there be a common and interoperable implementation for Coherent like 400ZR for shorter-distance applications, or will the solutions be diversified?
  • Will the local oscillator wavelength management kill the application of Coherent to ultra-short-reach uncooled applications?
  • Is it worth sending a remote light through a separate link for self-homodyne coherent detection?
  • Can coherent access really meet the end users’ stringent power/cost limit, and if so, how far we’re away from that?

This workshop will invite speakers from academia, system and module vendors, datacenter and access operators to provide a diversity of perspectives.


Di Che, Nokia Bell Labs, USA

Sam Palermo, Texas A&M University, USA

Paola Parolari, Politecnico di Milano, Italy

Clint Schow, University of California, Santa Barbara, USA


Hector Andrade, University of California, Santa Barbara, USA

Tao Gui, Huawei Technologies, China

Zhensheng Jia, Cable Labs, USA

Erji Mao, Google, USA

Radha Nagarajan, Marvell Technology, USA

Seb J. Savory, University of Cambridge, UnitedKingdom

Fabienne Saliou, Orange Labs, France

Matthew Sysak, Ayar Labs, USA

Yawei Yin, Microsoft, USA

Hongbin Zhang, Cisco, USA