Comparison on OM5-MMF and OM4-MMF Data Links with 32-GBaud PAM-4 Modulated Few-Mode VCSEL at 850 nm

Cheng Yi Huang, Huai Yung Wang, Cheng Han Wu, Wei Chi Lo, Cheng Ting Tsai, Chao Hsin Wu, Milton Feng, Gong Ru Lin

Research output: Contribution to journalArticlepeer-review


Based on the pre-emphasis 4-level pulse amplitude modulation (PAM-4) format at a symbol rate of 32 GBaud, the comparisons among optical PAM-4 data transmissions through back-To-back (BtB), 100-m OM4 multi-mode fiber (MMF), and 100-m OM5-MMF links are discussed in detail by employing the directly modulated few-Transverse-mode (FM) vertical cavity surface emitting laser (VCSEL) chip at 850 nm as the carrier. The bare FM-VCSEL chip exhibits an oxide-confined aperture of 5 μm to provide 3-4 transverse modes with low threshold current (Ith) of 0.25 mA and high optical power of 1.2 mW at a bias current of 38 Ith. The impendence of 65 Ω and the 3-dB bandwidth of 24 GHz are obtained by setting the DC point of the FM-VCSEL at 6.25 mA. With the bias current optimization and the pre-emphasis, the receiving bit error ratio (BER) of the 32-GBaud PAM-4 data meets the KP4-forward error correction criterion of 2.4 × 10-4, which enables the FM-VCSEL successfully achieving the 64-Gbit/s data stream transmission through the BtB and 100-m OM4-/OM5-MMF links. As compared to the BtB transmission with a BER of 2.5 × 10-8, replacing OM4 with OM5 for the 64-Gbit/s PAM-4 transmission reduces the receiving power penalty from 3.41 to 0.86 dB and improves the BER from 3.8 × 10-5 to 3.8 × 10-6. That is mainly attributed to the higher effective modal bandwidth and compensated modal and chromatic dispersions of the OM5-MMF as compared to the OM4-MMF when delivering the FM-VCSEL carried PAM-4 data stream.

Original languageEnglish (US)
Article number8839077
Pages (from-to)573-582
Number of pages10
JournalJournal of Lightwave Technology
Issue number3
StatePublished - Feb 1 2020


  • Fiber optics
  • infrared
  • optical interconnects
  • vertical cavity surface emitting lasers

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


Dive into the research topics of 'Comparison on OM5-MMF and OM4-MMF Data Links with 32-GBaud PAM-4 Modulated Few-Mode VCSEL at 850 nm'. Together they form a unique fingerprint.

Cite this