Four Wave Mixing (FWM)

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Four Wave Mixing (FWM)

• Spring 2004 EE290F
• Xiaoxue Zhao

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Contents

• Origin of FWM
• Effect on WDM systems
• Solutions
• Polarization Allocation
• Unequal Channel Spacing
• Dispersion Management

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Origin of FWM 1

• Third order nonlinearity
• Energy Conservation
• Momentum Conservationphase matching

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Origin of FWMPhase Matching 2
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Effects on WDM Systems 2

• Channel spacing and fiber dispersion are small
  enough

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Effects on WDM Systems 3

• Nonlinear Crosstalk

equally spacing, product terms fall at channel
frequency Coherent interference
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Effects on WDM Systems 4

• Bit pattern
• Power Depletion

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Effects on WDM SystemsSolutions

• Polarization Allocation
• Unequal spacing
• Dispersion management

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Polarization Allocation 5
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Polarization Allocation 5
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Polarization Allocation 5
Add polarization filter at the receiver end
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Unequal Channel Spacing 6
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Unequal Channel Spacing 6
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Dispersion-Management 4

• No dispersion-zero point
• Total accumulated dispersion near zero

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Dispersion Management 7

• Dispersion map for dispersion-compensating fiber
  (DCF)
• Small core area

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New Type of Fibers

• Large effective area fiber
• Nonzero dispersion shifted fiber (NZ-DSF)

large-effective-area fiber (red) suppressed
four-wave mixing crosstalk to -22.5 dB, compared
to -19.0 dB for NZ-DSF fiber (blue).
http//www.corning.com/opticalfiber/products__serv
ices/reprints/r1083.asp
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References

• 1 G.Agrawal Nonlinear Fiber Optics, 3rd
  edition
• 2 G Agrawal Fiber-Optics Communication
  Systems 3rd edition
• 3 Nori Sibata, Ralf Braun and Robert Waarts,
  IEEE J. Quantum Electron. QE23, 1205, 1987
• 4 Ivan Kaminow and Thomas Koch, OFT IIIA
• 5 C. Mahon, L. Olofsson, E. Bodtker, G.
  Jacobsen, IEEE Photon. Tech. Lett. 8,575, 1996
• 6 F. Forghieri, R. Tkach, A. Chroplyvy, J.
  Lightwave Tech, 13, 889 1995
• 7 R. Tkach, R. Derosier and et. al, IEEE
  Photon. Tech. Lett. 7, 1369, 1995