Xiang Zhou
Xiang Zhou is currently a Tech Lead within Google DC optics group, leading Next-Gen optical interconnection technologies and roadmap development. Prior to join Google, He was with AT&T Labs-Research (Middletown, NJ, USA, 2001 to 2013), conducting research on various aspects of long-haul optical transmission and networking technologies, From 1999 to 2001, he was with Nanyang Technological University, Singapore, as a Research Fellow. Xiang Zhou received his Ph. D degree from BUPT in 1999.
Dr. Zhou has extensive publications in top Journals and conferences in his field, including several record-setting ‘hero’ results, which have received wide media reports. He holds more than 50 US patents with a dozen more pending. He currently serves as an associate editor for J. Lightwave Technology and is an OSA fellow. He also served on the editorial board of Optics Express and in the Program Committee of a variety of technical conferences.
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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-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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Datacenter networks
Journal of Optics (2023) (to appear)
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This is an invited paper section, as part of an industry white paper, 2023 Roadmap on Optical Communication, to be published in Journal of Optics. This paper section reviews, from a high level, technology challenges and possible solutions to continue to scale datacenter network
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This is an OIF 800G LR standard contribution. This contribution proposes to revise 800G LR1 baseline link loss budget from 6dB at C-band wavelength to 8dB at O-band wavelength
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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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This is intended for IEEE802.3df contribution. In this contribution, we describe how to model four-wave-mixing (FWM) for datacenter interconnects systems, and why FWM could limit the achievable reach for 1.6Tb/s WDM-8 IM-DD systems
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This is intended for IEEE802.3df contribution. In this contribution, we describe the FEC requirements for 800GbE/1.6TbE optics from an operator's perspective, and how to make a fair comparison among different FEC options.
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This is on OFC conference workshop talk, discussing the use cases of low-latency optical interconnect technology in modern datacenter
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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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800G LR1 Use Cases and Requirements Revisit
Optical Internetworking Forum, https://www.oiforum.com/, https://www.oiforum.com/ (2021)
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This is contribution of campus networking application requirements to the OIF 800G-LR coherent-lite project.
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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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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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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 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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This is an invited OSA annual meeting talk. This talk reviews technology options and challenges to scale bandwidth and power for large-scale data center interconnects.
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Pluggable DWDM: Considerations For Campus and Metro DCI Applications
ECOC 2016 workshop presentation, VDE, Germany, Stresemannallee 15
60596 Frankfurt/Main
Germany (2016)
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This is a ECOC workshop talk. We will discuss, from Google’s perspective, the challenges facing datacenter campus and metro interconnection networks, and the potential of using pluggable tunable DWDM for both campus and metro applications
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This book chapter presents a systematic review on carrier recovery technologies recently developed for high-spectral efficiency coherent transmission systems.
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This paper presents a systematic review of several
digital signal processing (DSP)-enabled technologies recently
proposed and demonstrated for high spectral efficiency (SE)
400Gb/s – class and beyond optical networks. These include 1) a
newly proposed SE-adaptable optical modulation technology ⎯
time-domain hybrid quadrature amplitude modulation (QAM),
2) two advanced transmitter side digital spectral shaping
technologies ⎯ Nyquist signaling (for spectrally-efficient
multiplexing) and digital pre-equalization (for improving
tolerance toward channel narrowing effects), and 3) a newly
proposed training-assisted two-stage carrier phase recovery
algorithm that is designed to address the detrimental cyclic phase
slipping problem with minimal training overhead. Additionally,
this paper presents a novel DSP-based method for mitigation of
equalizer-enhanced phase noise impairments. It is shown that
performance degradation caused by the interaction between the
long-memory chromatic dispersion (CD) compensating
filter/equalizer and local oscillator (LO) laser phase noise can be
effectively mitigated by replacing the commonly used fast
single-tap phase-rotation-based equalizer (for typical carrier
phase recovery) with a fast multi-tap linear equalizer. Finally,
brief reviews of two high-SE 400Gb/s-class WDM transmission
experiments employing these advanced DSP algorithms are
presented.
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