7×149 Gbit/s PAM4 Transmission over 1 km Multicore Fiber for Short-Reach Optical Interconnects

Ozoliņš, Oskars; Pang, Xiaodan; Udaļcovs, Aleksejs; Lin, Rui; Kerrebrouck, Joris Van; Gan, Lin; Tang, Ming; Fu, Songnian; Schatz, Richard; Westergren, Urban; Jacobsen, Gunnar; Liu, Deming; Tong, Weijun; Torfs, Guy; Bauwelinck, Johan; Chen, Jiajia; Popov, Sergei; Yin, Xin

doi:10.1364/cleo_si.2018.sm4c.4

Cited by 7 publications

(12 citation statements)

References 11 publications

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“…We attribute the main implementation penalty to electrical components in the transmitter which could be remedied by improving the bandwidth and linearity in the electrical domain. Further improvement in the electrical signal generation scheme for PAM potentially would allow achieving better signal quality and, thus, improving the link latency thanks to a reduced FEC [21,31]. This would result in an even higher baud rate for multilevel signal transmission with the EML [19].…”

Section: Simulation Setup and Resultsmentioning

confidence: 99%

“…The current industrial solution for 400 GbE is based on four-level pulse amplitude modulation (PAM4) [8,9] instead of on-off keying (OOK) [19,28]. PAM4 reduces bandwidth requirements without excessive costs for sensitivity, digital signal processing (DSP), and transceiver complexity [29][30][31][32]. The higher spectral efficiency of advanced multilevel modulation formats, such as carrier-less amplitude and phase (CAP) or discrete multi-tone (DMT) modulations [33][34][35][36], can be beneficial to increase the bitrate of the single lane.…”

Section: Introductionmentioning

confidence: 99%

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100 Gbaud On–Off Keying/Pulse Amplitude Modulation Links in C-Band for Short-Reach Optical Interconnects

et al. 2021

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We experimentally evaluate the high-speed on–off keying (OOK) and four-level pulse amplitude modulation (PAM4) transmitter’s performance in C-band for short-reach optical interconnects. We demonstrate up to 100 Gbaud OOK and PAM4 transmission over a 400 m standard single-mode fiber with a monolithically integrated externally modulated laser (EML) having 100 GHz 3 dB bandwidth with 2 dB ripple. We evaluate its capabilities to enable 800 GbE client-side links based on eight, and even four, optical lanes for optical interconnect applications. We study the equalizer’s complexity when increasing the baud rate of PAM4 signals. Furthermore, we extend our work with numerical simulations showing the required received optical power (ROP) for a certain bit error rate (BER) for the different combinations of the effective number of bits (ENOB) and extinction ratio (ER) at the transmitter. We also show a possibility to achieve around 1 km dispersion uncompensated transmission with a simple decision feedback equalizer (DFE) for a 100 Gbaud OOK, PAM4, and eight-level PAM (PAM8) link having the received power penalty of around 1 dB.

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Section: Simulation Setup and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

100 Gbaud On–Off Keying/Pulse Amplitude Modulation Links in C-Band for Short-Reach Optical Interconnects

et al. 2021

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“…achieved by using simplest modulation formats, e.g., non-return to zero onoff-keying (NRZ-OOK) and partially responding signaling electrical duo-binary (EDB) [10]. 4level pulse amplitude (PAM4) [12] and discrete multi-tone (DMT) [7] are another two options for modulation, which can alleviate the baud rate and achieve high bandwidth efficiency. By exploiting multiplexing techniques, such as wavelength division multiplexing (WDM) [7], spatial division multiplexing (SDM) based on multicore/multimode fiber [12] and their combination [11], the per-fiber capacity of the interconnect can be further boosted.…”

Section: Optical Transmission For Communication Between Resourcesmentioning

confidence: 99%

“…In the disaggregated DC, the transceivers should be small and simple to be implemented or integrated on the resource unit in a cost-efficient manner. For the transceiver side, vertical-cavity surface emitting lasers (VCSELs) [9,11,12] and silicon photonic (SiP) integrated circuit techniques [7] are two main candidates to address the challenges in terms of cost and footprint. VCSELs are being widely used in short-reach optical communications, usually integrated with SDM systems.…”

Section: Optical Transmission For Communication Between Resourcesmentioning

confidence: 99%

Disaggregated Data Centers: Challenges and Trade-offs

Lin

Cheng²,

Andrade³

et al. 2020

IEEE Commun. Mag.

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Resource utilization of modern data centers is significantly limited by the mismatch between the diversity of the resources required by running applications and the fixed amount of hardwired resources (e.g., number of central processing unit CPU cores, size of memory) in the server blades. In this regard, the concept of function disaggregation is introduced, where the integrated server blades containing all types of resources are replaced by the resource blades including only one specific function. Therefore, disaggregated data centers can offer high flexibility for resource allocation and hence their resource utilization can be largely improved. In addition, introducing function disaggregation simplifies the system upgrade, allowing for a quick adoption of new generation components in data centers. However, the communication between different resources faces severe problems in terms of latency and transmission bandwidth required. In particular, the CPU-memory interconnects in fully disaggregated data centers require ultra-low latency and ultrahigh transmission bandwidth in order to prevent performance degradation for running applications. Optical fiber communication is a promising technique to offer high capacity and low latency, but it is still very challenging for the state-of-the-art optical transmission technologies to meet the requirements of the fully disaggregated data centers. In this paper, different levels of function disaggregation are investigated. For the fully disaggregated data centers, two architectural options are presented, where optical interconnects are necessary for CPU-memory communications. We review the state-of-the-art optical transmission technologies and carry out performance assessment when employing them to support function disaggregation in data centers. The results reveal that function disaggregation does improve the efficiency of resource usage in the data centers, although the bandwidth provided by the state-of-the-art optical transmission technologies is not always sufficient for the fully disaggregated data centers. It calls for research in optical transmission to fully utilize the advantages of function disaggregation in data centers. I. INTRODUCTION Cloud computing is one of the major services provided by modern data centers (DCs), where users are able to freely choose resources and operating systems (OSs) for running their applications without considering the underlying

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“…Extensive work has been reported on SDM transmission carrying different modulation formats on DCN links, including NRZ [75][76][77], EDB [75][76][77], PAM4 [78][79][80][81] and DMT [24,82]. In [77], a BiCMOS chip-based real-time 100Gbps/λ/core NRZ and EDB over 10km 7-core MCF SDM interconnects is experimentally demonstrated.…”

Section: B Modulation Formats and Dspmentioning

confidence: 99%

Enabling Technologies for Optical Data Center Networks: Spatial Division Multiplexing

Westergren

Chen

Agrell

et al. 2020

J. Lightwave Technol.

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With the continuously growing popularity of cloud services, the traffic volume inside the data centers is dramatically increasing. As a result, a scalable and efficient infrastructure for data center networks (DCNs) is required. The current optical DCNs using either individual fibers or fiber ribbons are costly, bulky, hard to manage, and not scalable. Spatial division multiplexing (SDM) based on multicore or multimode (few-mode) fibers is recognized as a promising technology to increase the spatial efficiency for optical DCNs, which opens a new way towards high capacity and scalability. This tutorial provides an overview of the components, transmission options, and interconnect architectures for SDM-based DCNs, as well as potential technical challenges and future directions. It also covers the co-existence of SDM and other multiplexing techniques, such as wavelength-division multiplexing and flexible spectrum multiplexing, in optical DCNs.

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7×149 Gbit/s PAM4 Transmission over 1 km Multicore Fiber for Short-Reach Optical Interconnects

Abstract: We transmit 80 Gbaud/λ/core PAM4 signal enabled by 1.55 µm EML over 1 km 7-core fiber. The solution achieves single-wavelength and single-fiber 1.04 Tbit/s post-FEC transmission enhancing bandwidth-density for short-reach optical interconnects.

Cited by 7 publications

References 11 publications

100 Gbaud On–Off Keying/Pulse Amplitude Modulation Links in C-Band for Short-Reach Optical Interconnects

100 Gbaud On–Off Keying/Pulse Amplitude Modulation Links in C-Band for Short-Reach Optical Interconnects

Disaggregated Data Centers: Challenges and Trade-offs

Enabling Technologies for Optical Data Center Networks: Spatial Division Multiplexing

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