Hong Liu
Hong Liu is a Google Fellow at Machine Learning, Systems and Cloud AI (MSCA), where she is involved in the system architecture and interconnect for a large-scale computing platform. Her research interests include high speed signaling, optical architecture and interconnection for datacenter networking and machine learning. Prior to joining Google, Hong was a Member of Technical Staff at Juniper Networks, where she worked on the architecture and design of network core routers and multi-chassis switches. She holds 55 U.S. patents in the areas of photonic devices, datacenter networks, and optical communications. Hong received her Ph.D in electrical engineering from Stanford University, is an OSA Fellow.
Authored Publications
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This is an invited OFC 2024 conference workshop talk regarding a new type of lower-power datacenter optics design choice: linear pluggable optics. In this talk I will discuss the fundamental performance constraints facing linear pluggable optics and their implications on DCN and ML use cases
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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 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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This is an OFC 2022 conference panel talk. We review from high level about the right technology choice for 1.6Tb/s data center optics interconnects
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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 workshop talk we will discuss the potential and value of flexible modulation formats and constellation shaping for datacenter interconnection bandwidth scaling
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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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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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