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Multicast-enabled high-speed VCsEL technology for flexible data center networks

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Optoelectronics Letters 2018年第6期14卷 438-441页

作者： G.M.Isoe s.wassin T.B.Gibbon Center for Broadband Communication Nelson Mandela University

We experimentally demonstrate the multiple signal modulation on a single class 10 G vertical cavity surface emitting laser(VCsEL) carrier at 1 310 nm for next generation multicast-enabled data center networks. A 10 Gbit/s data signal is directly modulated onto a single mode VCsEL carrier. To maximize carrier spectral efficiency, a 2 GHz reference frequency(RF) clock tone is simultaneously modulated on the VCsEL phase attribute. The inherent VCsEL orthogonal polarization bistability with changing bias current is further exploited in transmission of a polarization based pulse per second(PPs) timing clock signal. Therefore, we simultaneously transmit a 10 Gbit/s directly modulated data, 2 GHz phase modulated RF and a polarization-based PPs clock signals using a single mode 10 GHz bandwidth VCsEL carrier. It is the first time that a single class 10 G VCsEL carrier is reported to transmit a directly modulated data, phase modulated RF clock and polarization based PPs timing signal simultaneously in a single wavelength. A of G.652 single mode fibre(sMF) transmission over 3.21 km is experimentally attained. A receiver sensitivity of-15.60 dBm is experimentally obtained for the directly modulated 10 Gbit/s data signal. A 3.21-km-long sMF transmission introduces a penalty of 0.23 dB to the data signal. The contribution of a 2 GHz phase modulated RF and a polarization-based PPs clock signal to this penalty is found to be 0.03 dB. An RF single-side band(ssB) phase noise values of -82.36 dBc/Hz and -77.97 dBc/Hz are attained without and with simultaneous directly modulated data and polarization-based PPs clock signals respectively for a 3.21-km-long sMF transmission. This work provides an alternative efficient and cost effective technique for simultaneous high-speed multiple information transmission to different network nodes within a data center network through shared network infrastructure.

关键词： VCsEL Multicast-enabled data center networks

Time and reference frequency transfer over 850 nm VCsEL for digital telecommunication network synchronization

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Optoelectronics Letters 2019年第3期15卷 209-212页

作者： G.M.Isoe s.wassin A.W.R.Leitch T.B.Gibbon Centre for Broadband Communication Nelson Mandela University

Accurate time transfer and synchronization between different network nodes is a key functional requirement in digital communication. Developments in optical fiber-based frequency dissemination techniques have improved optical frequency stability over time to much lower levels. In this work, we experimentally present the reference frequency transfer employing 850 nm vertical cavity surface emitting laser(VCsEL) over 100.3 m OM3 multimode fiber for synchronization of clocks on networked devices such as servers and racks/pod at different data center network nodes. A low-cost power-efficient multimode VCsEL with central wavelength at 844.26 nm is directly modulated with a 2 GHz reference frequency(RF) clock signal, and transferred over 100.3 m of OM3 multimode fiber. The single side band(ssB) phase noise of-104.62 dBc/Hz and-100.70 dBc/Hz is experimentally measured at back-to-back(B2 B) and 100.3 m OM3 multimode fiber transmission respectively at a 1 kHz frequency offset. The jitter stability of 0.14 ps and 0.15 ps is experimentally achieved at B2 B and 100.3 m fiber transmission, respectively. This work provides an alternative viable approach for the development of time keeping devices in high-speed short-reach optical communication systems.

关键词： VCsEL

Transmission of precise phase coherent optical signals using a VCsEL stabilization system

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Optoelectronics Letters 2019年第3期15卷 200-203页

作者： shukree wassin George Isoe Andrew Leitch Tim Gibbon Centre for Broadband Communication Physics DepartmentNelson Mandela University

To improve the time and frequency reference standards used for radio astronomy and high precision atomic physics applications, we describe a novel stable frequency transmission technique. The approach uses a vertical-cavity surface-emitting laser(VCsEL) based phase correction actuator. Using a frequency mixing process for feedback control, the phase noise induced along the 26 km G.655 optical fibre link was actively reduced. This was achieved by using a 1 310 nm dither controlled VCsEL phase error correction actuator together with the inherent chromatic dispersion properties of the fibre. The technique corrects phase noise and optical signal drift along the fibre at the transmission end. Fractional frequency instabilities across the G.655 fibre link of 4.44×10-12 at 1 s and 4.86×10-14 at 104 s are successfully reported.

关键词： VCsEL Transmission of precise phase coherent optical signals using a VCsEL stabilization system