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Electronics and Telecommunications Research Institute (한국전자통신연구원)
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Optimum thickness of GaAs top layer in AlGaAs-based 850 nm VCSELs for 56 Gb/s PAM-4 applications

  • Yu, Shin-Wook (Department of Electronic and Computer Engineering, Ajou University) ;
  • Kim, Sang-Bae (Department of Electronic and Computer Engineering, Ajou University)
  • Received : 2020.05.06
  • Accepted : 2020.12.21
  • Published : 2021.10.01
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Abstract

We studied the influence of GaAs top-layer thickness on the small-signal modulation response and 56 Gb/s four-level pulse-amplitude modulation eye quality of 850 nm vertical-cavity surface-emitting lasers (VCSELs). We considered the proportionality of the gain-saturation coefficient to the photon lifetime. The simulation results that employed the transfer-matrix method and laser rate equations led to the conclusion that the proportionality should be considered for proper explanation of the experimental results. From the obtained optical eyes, we could determine an optimum thickness of the GaAs top layer that rendered the best eye quality of VCSEL. We also compared two results: one result with a fixed gain-saturation coefficient and the other that considered the proportionality. The former result with the constant gain-saturation coefficient demonstrated a better eye quality and a wider optimum range of the GaAs top-layer thickness because the resultant higher damping reduced the relaxation oscillation.

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References

  1. J. Lavrencik et al., DSP-enabled 100 Gb/s PAM-4 VCSEL MMF links, J. Light. Technol. 35 (2017), no. 15, 3189-3196. https://doi.org/10.1109/JLT.2017.2683941
  2. D. Sadot et al., Single channel 112 Gb/s PAM4 at 56 gbaud with digital signal processing for data center applications, Opt. Exp. 23 (2015), no. 2, Article no. 222533.
  3. E. Szczerba et al., 4-PAM for high-speed short-range optical communications, IEEE/OSA J. Opt. Commum. Netw. 4 (2012), no. 11, 885-894. https://doi.org/10.1364/JOCN.4.000885
  4. S. M. R. Motaghiannezam et al., 51.56 Gbps PAM4 transmission over up to 2.3 km OM4 fiber using mode selective VCSEL, in Proc. OFC Conf. (San Diego, CA, USA), Mar. 2018, Article no. M1I.3.
  5. H. Y. Cao et al., Single-mode VCSEL for pre-emphasis PAM-4 transmission up to 64 Gbit/s over 100- 300 m in OM4 MMF, Photonics Res. 6 (2018), no. 7, 666-673. https://doi.org/10.1364/PRJ.6.000666
  6. IEEE Computer Society, IEEE standard for Ethernet, IEEE, 2018.
  7. P. Westbergh et al., Impact of photon lifetime on high-speed VCSEL performance, IEEE J. Sel. Top. Quantum Electron. 17 (2011), no. 6, 1603-1613. https://doi.org/10.1109/JSTQE.2011.2114642
  8. C. Y. Tsai et al., Nonlinear gain coefficients in semiconductor quantum-well lasers: Effects of carrier diffusion, capture, and escape, IEEE J. Sel. Top. Quantum Electron. 1 (1995), no. 2, 316-330. https://doi.org/10.1109/2944.401211
  9. F. Kariminezhad et al., Impact of gain compression factor on modulation characteristics of InGaAs/GaAs self-assembled quantum dot lasers, J. Theoretical Appl. Phys. 10 (2016), no. 4, 281-287. https://doi.org/10.1007/s40094-016-0227-7
  10. M. Willatzen, T. Takahashi, and Y. Arakawa, Nonlinear gain effects due to carrier heating and spectral hole burning in strained-quantum-well lasers, IEEE Photonics Technol. Lett. 4 (1992), no. 7, 682-685. https://doi.org/10.1109/68.145237
  11. T. Y. Kim and S. B. Kim, Design of 850 nm vertical-cavity surface-emitting lasers by using a transfer matrix method, J. Inst. Electr. Eng. Korea SD 41 (2004), no. 1, 35-46.
  12. M. W. Jang and S. B. Kim, A study on low-current-operation of 850 nm oxide VCSELs using a large-signal circuit model, J. Inst. Electr. Eng. Korea SD 43 (2006), no. 10, 10-21.
  13. E. P. Haglund et al., Impact of damping on high-speed large signal VCSEL dynamics, J. Light. Technol. 33 (2015), no. 4, 795-801. https://doi.org/10.1109/JLT.2014.2364455
  14. T. Lengyel et al., Impact of damping on 50 Gbps 4-PAM modulation of 25G class VCSELs, IEEE J. Light. Technol. 35 (2017), no. 19, 4203-4209. https://doi.org/10.1109/JLT.2017.2727549