Comparison of High-Speed PAM4 and QAM-OFDM Data Transmission Using Single-Mode VCSEL in OM5 and OM4 MMF Links

Cheng Yi Huang, Huai Yung Wang, Cheng Han Wu, Chih Hsien Cheng, Cheng Ting Tsai, Chao Hsin Wu, Milton Feng, Gong Ru Lin

Research output: Contribution to journalArticle

Abstract

To realize the superiority of data transmission with reduced modal dispersion in OM4-and OM5-mulitmode fiber (MMF), a single transverse mode (SM) vertical cavity surface emitting laser (VCSEL), directly encoded with large-capacity data formats for transmissions in OM5-MMF and OM4-MMF, are compared. The SM-VCSEL contains a 12-μm mesa formed by double-oxidized AlGaAs layers, which confines a current-flow area within an aperture of 3 μm. The SM-VCSEL is lasing with a carrier-to-noise ratio of 34.4 dB and a linewidth of 0.05 nm. The SM-VCSEL is biased at 10Ith to provide a modulation bandwidth of 21.4 GHz and a relative intensity noise of-138 dBc/Hz. By encoding the SM-VCSEL with four-level pulse amplitude modulation (PAM-4) at 64 Gbit/s, the bit error ratio (BER) of 32-GBaud PAM-4 data is improved from 7.9 × 10-5 to 4.9 × 10-5 under a KP4-FEC criterion by replacing OM4-MMF with OM5-MMF. After OM5-MMF transmission, a bathtub BER plot shows bottom-eye, middle-eye, and top-eye jitter tolerances of 9.3, 10.6, and 7.1 ps, which are much wider than 6.9, 10.1, and 6.5 ps for OM4-MMF, respectively. When encoding the 16-QAM OFDM at 100 Gbit/s, OM5-MMF allows data transmission at 96-Gbit/s with a corresponding error vector magnitude, signal-to-noise ratio, and BER of 16.7%, 15.4 dB, and 3.6 × 10-3 under preleveling at a slope of 0.3 dB/GHz. Because of the high effective modal bandwidth and low modal dispersion of the OM5-MMF, a relatively low receiving power penalty of 0.1 dB between 100-m and back-to-back (BtB) transmissions is obtained with either the pre-emphasized PAM-4 or the pre-leveled QAM-OFDM data format. By contrast, the receiving power penalty is 1.04 dB between 100 m and BtB cases during OM4-MMF transmission.

Original languageEnglish (US)
Article number8662674
JournalIEEE Journal of Selected Topics in Quantum Electronics
Volume26
Issue number4
DOIs
StatePublished - Jul 1 2020

Keywords

  • data center
  • M-ary QAM
  • MMF
  • OFDM
  • OM4
  • OM5
  • single-mode
  • Vertical cavity surface-emitting laser (VCSEL)

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

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