An Analysis of Signal-to-Noise Ratio and Design Parameters of a Terahertz Optical Asymmetric Demultiplexer

Deyu Zhou, Koo Il Kang, Ivan Glesk, Paul R. Prucnal

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Analysis of the signal-to-noise ratio (SNR) as a function of the component parameters in a terahertz optical asymmetric demultiplexer (TOAD) can help optimize its performance as a demultiplexer or as a router in an optical time division multiplexed network. The analysis presented here accounts for crosstalk due to deviation from a perfect 3 dB splitting ratio in the TOAD's 2×2 coupler, and the degradation of SNR due to fluctuations in the control pulse energy. The spontaneous emission noise output of the semiconductor optical amplifier (SOA) contained in the TOAD is simulated under different degrees of saturation. The analysis indicates that leakage due to the asymmetric placement of the SOA contributes significantly to the crosstalk. To achieve a SNR of 21.5 dB or higher in a 100 Gb/s system, one must use a 2 × 2 coupler that deviates less than 1% from a perfect 3 dB splitting ratio. Also, control pulse energy fluctuations must be less than 10% for a 20-GHz bandwidth electronic receiver. Novel crosstalk-free designs are proposed and analyzed which meet the stringent requirements of current TOAD devices. A significant enhancement in SNR is predicted when the SOA is operated near the optimal saturation point.

Original languageEnglish (US)
Pages (from-to)298-307
Number of pages10
JournalJournal of Lightwave Technology
Issue number2
StatePublished - Feb 1 1999

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


  • Demultiplexers
  • Fiber-optic communications
  • Optical time division multiplexing
  • Semiconductor optical amplifier
  • Signal-to-noise ratio


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