access icon free VCSEL-based optical links in burst-mode slow optical power ramp-up and how to achieve ultra-short wake-up times

Optical links in datacentres operate mainly in burst mode. The utilisation might be as low as 10%, i.e. most of the time the link is idle, but still consumes power. It would therefore be desirable to put these links into a low-power sleep mode during idle signal by reducing the bias, and to operate the electronics and laser only when data is actually being transmitted. The laser is typically implemented with vertical cavity surface-emitting lasers (VCSELs). VCSELs should not be biased below their threshold current as otherwise an extensive turn-on delay will be incurred. A significant wake-up time is still observed in VCSELs even if the bias is not reduced during idle and only logic zeros are transmitted. With reduced bias, an unacceptable wake-up time is observed. The authors present measured data and propose a high-amplitude wake-up pulse at the beginning of the data burst, to significantly speed up the wake-up time. Measurements show the effectiveness of this pulse.

Inspec keywords: laser cavity resonators; optical communication equipment; computer centres; optical pulse generation; surface emitting lasers; optical links

Other keywords: idle signal; burst-mode slow optical power ramp-up; ultra-short wake-up times; high-amplitude wake-up pulse; VCSEL-based optical links; wake-up time; turn-on delay; sleep mode; datacentres; logic zeros; vertical cavity surface-emitting laser; data burst

Subjects: Optical communication equipment; Design of specific laser systems; Laser beam modulation, pulsing and switching; mode locking and tuning; Laser beam modulation, pulsing and switching; mode locking and tuning; Semiconductor lasers; Free-space optical links; Lasing action in semiconductors; Ultrafast optical techniques; Laser resonators and cavities; Optical communication devices, equipment and systems; Laser resonators and cavities

References

    1. 1)
      • 2. Doany, F.E., Kuchta, D.M., Kash, J.A.: ‘Measurement of picosecond transverse mode dynamics in data communication VCSELs beyond 10 Gbit/s’. Conf. Lasers and Electro-Optics (CLEO), San Francisco, CA, December 2004, vol. 1, paper CTuAA4.
    2. 2)
      • 4. US Patent Application Number: 15/478789: ‘VCSEL based optical links in burst mode’, 4.4.2017.
    3. 3)
      • 7. Menolfi, M., Hertle, J., Toifl, T., et al: ‘28 Gb/s source-series terminated TX in 32nm CMOS SOI’. 2012 IEEE Int. Solid State Circuits Conf., pp. 334336, doi: 10.1109/ISSCC.2012.6177035.
    4. 4)
      • 5. Finisar application note: ‘Pulsed operation of VCSELs for high peak powers’, https://www.finisar.com/sites/default/files/downloads/application_note_pulsed_operation_of_vcsels_for_high_peak_powers.pdf.
    5. 5)
      • 3. Petermann, K.: ‘Laser diode modulation and noise’ (Kluwer Academic Publisher, 1988).
    6. 6)
      • 1. Roy, A., Zeng, H., Bagga, G., et al: ‘Inside the social network's datacenter network’. Sigcomm, 2015, www.sigcomm.org/node/3804, doi: http://dx.doi.org/10.1145/2829988.2787472.
    7. 7)
http://iet.metastore.ingenta.com/content/journals/10.1049/el.2017.2513
Loading

Related content

content/journals/10.1049/el.2017.2513
pub_keyword,iet_inspecKeyword,pub_concept
6
6
Loading
Correspondence
This article has following corresponding article(s):
in brief