70Gb/s optical intra-connects in data centers based on band-limited devices
With the ever development of optical data-center intra-connects, the realization of high-capacity and low-cost optical communication links among severs in data centers has been more and more popular in the industry. Recently, a research result, completed by the researchers from Peking University, shows that a 70Gb/s optical link has been experimentally demonstrated using the 18GHz band-limited VCSEL and multimode fibers, which makes it possible to realize high-speed data transmission in data centers only by low-cost and band-limited devices.
SCIENCE CHINA Information Sciences has just accepted a paper under the title "A 70 Gbps NRZ optical link based on 850 nm band-limited VCSEL for data-center intra-connects" which is authored by Zhongwei TAN, Chuanchuan YANG, et al.
This research builds the corresponding optical communication link and conducts the experimental work. The receivers utilize the forward-feed equalization (FFE), combined with the max likelihood sequence estimation (MLSE), to process the received data, efficiently eliminating the inter symbol interference (ISI) caused by the limited bandwidth and realizing the 70 Gb/s data transmission.
With the development of Internet, the demand for mass data transmission and processing is ever growing. Especially for hyper-scale data centers, it is significant to build the high-capacity and low-cost communication links for sharing the processing ability and storage ability among servers. Based on the above, optical data-center intra-connects develop quickly, and how to realize the optical links with high speed and low cost becomes extraordinarily important. The previous researches in this field mostly focused on the high transmission rate and employed large-bandwidth VCSELs (25GHz or so, typically). However, the large-bandwidth VCSELs lead to extremely high cost, which is against the original intention for low-cost optical intra-connects in data centers.
Based on the status, this research mainly focuses on the 18GHz band-limited commercial VCSEL, for cost saving, uses proper equalization method to suppress the ISI and realizes high data rate in short-reach data-center interconnects.
Dr. Chuanchuan YANG, the corresponding author of this paper, believes that this research is of great directive significance for the band-limit and cost-effective VCSELs to be utilized in the data centers for the high-speed optical interconnects among severs in the future.
The results enrich the research work in the field of short-distance optical intra-connects in data centers and mainly research on the communication characteristic for band-limit devices. It has important scientific significance and reference value for realizing high-capacity and low-cost data center intra-connects.
The research work is completed cooperated with Prof. Fan ZHANG, Prof. Ziyu WANG, Ph.D. candidate Yixiao ZHU, Master students Zhaopeng XU and Kaiheng ZOU, from Peking University. "To our best knowledge", wrote the researchers, "the results reported the highest data baud rate for an 18-GHz-class 850 nm VCSEL based optical link."
This research was funded by the National Natural Science Foundation, China (Nos. 61275005, 61475004).
See the article: Zhongwei TAN, Chuanchuan YANG, Yixiao ZHU, et al. A 70 Gbps NRZ optical link based on 850 nm band-limited VCSEL for data-center intra-connects. Science China Information Sciences, 2017 (in press), doi: 10.1007/s11432-017-9276-y.
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