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Low Thermal Sensitivity Hollow Core Fiber for Optically-Switched Data Centers

Low Thermal Sensitivity Hollow Core Fiber for Optically-Switched Data Centers
Low Thermal Sensitivity Hollow Core Fiber for Optically-Switched Data Centers
Optical switches offer several benefits over electronics switches, including better scalability, lower power consumption, and lower latency. However, their implementation faces several challenges, including electronic transceivers to be able to support sub-nanosecond clock and data recovery time. This is required to efficiently handle data center traffic that is dominated by small data packets. Recent research shows that, scalable and sub-nanosecond data recovery can be achieved by synchronizing the clocks of all end-points connected to an optical switch in frequency and phase. In such a system, thermally-induced change of propagation time through standard single mode fiber (SMF-28) necessitates the clock phases to be tracked due to variations in the data centers temperature. Hollow core fiber has been shown to have a thermal coefficient of delay 20 times smaller than SMF-28, offering potential to simplify the clock phase tracking and to increase the distance scale of data center networks. In this paper, we show how the low thermal coefficient of delay in hollow core fiber enables sub-nanosecond optical switching system with only initial frequency and phase synchronization. We obtained error-free real-time transmission of 60 ns packets over 1 km clock and 1 km hollow core data fiber with under 625 ps clock recovery time in both a point-to-point and a 2-to-1 optically switched 25.6 Gb/s real-time system. Based on our results, we estimate that sub-nanosecond clock recovery can be achieved for a 100 m size data center cluster interconnected by an optical switch using hollow core fiber, frequency synchronization and only a single phase calibration at the start-up.
0733-8724
2703-2709
Clark, Kari A.
d354d373-db12-4016-9245-8de43ca568bb
Chen, Yong
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Numkam Fokoua, Eric R.
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Bradley, Tom
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Poletti, Francesco
9adcef99-5558-4644-96d7-ce24b5897491
Richardson, David J.
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Bayvel, Polina
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Slavík, Radan
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Liu, Zhixin
01f60f1d-54b7-4c19-b3f3-9550f9d77733
Clark, Kari A.
d354d373-db12-4016-9245-8de43ca568bb
Chen, Yong
0bfb3083-4cd2-4463-a7a4-f48c4158b15a
Numkam Fokoua, Eric R.
cca13dcd-4443-4638-b9b4-d2dcb1dd100a
Bradley, Tom
d4cce4f3-bb69-4e14-baee-cd6a88e38101
Poletti, Francesco
9adcef99-5558-4644-96d7-ce24b5897491
Richardson, David J.
ebfe1ff9-d0c2-4e52-b7ae-c1b13bccdef3
Bayvel, Polina
0f0922e3-b79a-490f-8e50-e2e098b3e102
Slavík, Radan
2591726a-ecc0-4d1a-8e1d-4d0fd8da8f7d
Liu, Zhixin
01f60f1d-54b7-4c19-b3f3-9550f9d77733

Clark, Kari A., Chen, Yong, Numkam Fokoua, Eric R., Bradley, Tom, Poletti, Francesco, Richardson, David J., Bayvel, Polina, Slavík, Radan and Liu, Zhixin (2020) Low Thermal Sensitivity Hollow Core Fiber for Optically-Switched Data Centers. Journal of Lightwave Technology, 38 (9), 2703-2709. (doi:10.1109/JLT.2020.2979143).

Record type: Article

Abstract

Optical switches offer several benefits over electronics switches, including better scalability, lower power consumption, and lower latency. However, their implementation faces several challenges, including electronic transceivers to be able to support sub-nanosecond clock and data recovery time. This is required to efficiently handle data center traffic that is dominated by small data packets. Recent research shows that, scalable and sub-nanosecond data recovery can be achieved by synchronizing the clocks of all end-points connected to an optical switch in frequency and phase. In such a system, thermally-induced change of propagation time through standard single mode fiber (SMF-28) necessitates the clock phases to be tracked due to variations in the data centers temperature. Hollow core fiber has been shown to have a thermal coefficient of delay 20 times smaller than SMF-28, offering potential to simplify the clock phase tracking and to increase the distance scale of data center networks. In this paper, we show how the low thermal coefficient of delay in hollow core fiber enables sub-nanosecond optical switching system with only initial frequency and phase synchronization. We obtained error-free real-time transmission of 60 ns packets over 1 km clock and 1 km hollow core data fiber with under 625 ps clock recovery time in both a point-to-point and a 2-to-1 optically switched 25.6 Gb/s real-time system. Based on our results, we estimate that sub-nanosecond clock recovery can be achieved for a 100 m size data center cluster interconnected by an optical switch using hollow core fiber, frequency synchronization and only a single phase calibration at the start-up.

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Low Thermal Sensitivity Hollow Core Fiber for Optically-Switched Data Centers - Accepted Manuscript
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Accepted/In Press date: 29 February 2020
e-pub ahead of print date: 6 March 2020
Published date: 1 May 2020

Identifiers

Local EPrints ID: 441659
URI: http://eprints.soton.ac.uk/id/eprint/441659
ISSN: 0733-8724
PURE UUID: 7af4e6c3-4d03-44e9-8828-4b8f1b4506d1
ORCID for Yong Chen: ORCID iD orcid.org/0000-0003-0383-6113
ORCID for Tom Bradley: ORCID iD orcid.org/0000-0001-6568-5811
ORCID for Francesco Poletti: ORCID iD orcid.org/0000-0002-1000-3083
ORCID for David J. Richardson: ORCID iD orcid.org/0000-0002-7751-1058
ORCID for Radan Slavík: ORCID iD orcid.org/0000-0002-9336-4262

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Date deposited: 23 Jun 2020 16:46
Last modified: 24 Jun 2020 00:35

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