Ryohei Urata
Dr. Ryohei Urata is currently a Principal Engineer/Director in the Platforms Optics Group, where he has defined/developed Google's datacenter optical technologies and corresponding roadmap for the past decade. Prior to joining Google, he was a research specialist at NTT Photonics Laboratories, Japan. He has over 150 patents, publications, and presentations in the areas of optical interconnect, switching, and networking. He received the B.S. degree in engineering physics from the University of California at Berkeley (Highest Honors), and the M.S. and Ph.D. degrees in electrical engineering from Stanford University (Stanford Graduate Fellow). He was elected an Optica/OSA Fellow in 2022.
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Google Publications
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We review state-of-the-art datacenter technologies for 800G, 1.6T and beyond interconnect speeds, focusing on 200G per-lane IM-DD (intensity modulated-direct detect) and 800G-LR1 coherent-lite transmissions.
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We review state of art datacenter interconnect technologies for 800G, 1.6T and beyond networking speeds, with a special emphases on 200G per-lane IM-DD and 800G-LR1 coherent-lite
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We discuss technology options and challenges for beyond 1Tb/s intra-datacenter interconnect bandwidth scaling, with a focus on pulse amplitude modulation (PAM)-based intensity modulation-direct detection (IM-DD) and baud-rate digital signal processing (DSP)-based coherent technology.
We show that a flexible PAM (FlexPAM) technique with fine granularity of bandwidth/spectral efficiency (in terms of bits/symbol) could bring significant value for 200Gb/s per lane or per dimension bandwidth scaling.
For baud-rate sampled coherent technology, we propose a much simplified DSP architecture which could bring down coherent DSP power close to that of IM-DD PAM technology. We also propose two new phase noise tolerant, 5 bits per symbol, 2D coherent modulation formats to lower the requirement on laser linewidth.
To conclude, we present a comparative study of IM-DD PAM versus coherent PM-QAM (polarization multiplexed-quadrature amplitude modulation) for 200Gb/s per dimension throughput scaling in terms of achievable link loss/reach budget, power consumption, implementation complexity, as well as fan-out granularity.
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Beyond 1Tb/s Datacenter Interconnect Technology: Challenges and Solutions
OFC 2019 conference proceedings, OSA, The Optical Society
2010 Massachusetts Ave, NW
Washington, DC 20036 USA (2019)
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We discuss challenges and solutions for beyond 1Tb/s intra-datacenter bandwidth scaling, with a focus on the FlexPAM-based direct detection and the baud-rate DSP enabled coherent detection.
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In this presentation, we will discuss Google’s intra-datacenter networks and interconnect. We will first review the evolution of datacenter interconnects and networking over the past decade, then outline future technology directions which will be needed to keep pace with the requirements and growth of the datacenter.
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This paper reviews over decade of technology evolution and advancement of datacenter optical interconnect, which is mainly driven by the explosive bandwidth demand growth of web and cloud based services. Emerging trend and technical options to scale bandwidth well beyond 400Gb/s have also been discussed.
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Increasing demands for web and cloud-based services have been driving exponential growth of datacenter bandwidth. This paper discusses, from Google’s perspective, emerging challenges and possible technical solutions to scale intra-datacenter and intra-campus interconnection network bandwidth.
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In this presentation, we will review the evolution of Google’s intra-datacenter interconnects and networking over the past decade, then outline future technology directions which, along with a more holistic design approach, will be needed to keep pace with the requirements and growth of the datacenter.
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We give an overview of optical interconnect requirements for large scale datacenters. We then make a comparison between silicon photonics technologies and more traditional options in meeting these requirements.
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We discuss the trend in fiber optic technology developments to fulfill the scaling requirements of datacenter networks.
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Optical Interconnects for Scale-Out Data Centers
Amin Vahdat
Optical Interconnects for Future Data Center Networks, Springer, Avenel, NJ (2013), pp. 17-31
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We review the architecture of modern datacenter networks, as well as their scaling challenges; we then present opportunities and needs for emerging optical technologies to support datacenter scaling.
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Silicon Photonics for Optical Access Networks
Pedram Dashti
Chris Johnson
Group IV Photonics, IEEE, Washington DC (2012), pp. 3
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We highlight promising developments and directions in silicon photonics for realizing cost effective WDM-PON: photonic integration for integrated WDM transceivers at the OLT and widely tunable laser technologies for achieving a high performance, colorless ONU.
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High Performance, Low Cost, Colorless ONU for WDM-PON
Chris Johnson
Optical Fiber Communication (OFC) Conference 2012, OSA, Washington DC
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We give an overview of key technologies for realizing WDM-PON. In particular, we highlight promising developments and directions in widely tunable laser technologies for achieving a high performance, colorless ONU at the cost points required for access networks.
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