Cross-phase modulation

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Cross-phase modulation (XPM) is a nonlinear optical effect where one wavelength of light can affect the phase of another wavelength of light through the optical Kerr effect. When the optical power from a wavelength impacts the refractive index, the impact of the new refractive index on another wavelength is known as XPM.

Applications of XPM[edit]

Cross-phase modulation can be used as a technique for adding information to a light stream by modifying the phase of a coherent optical beam with another beam through interactions in an appropriate non-linear medium. This technique is applied to fiber optic communications.

XPM in DWDM applications[edit]

In DWDM applications with intensity modulation and direct detection (IM-DD) the effect of XPM is a two step process: First the signal is phase modulated by the copropagating second signal. In a second step dispersion leads to a transformation of the phase modulation into a power variation. Additionally the dispersion results in a walk-off between the channels and thereby reduces the XPM-effect.

Advantages of XPM[edit]

  • Nonlinear Pulse Compression
  • Passive mode locking
  • Ultra fast optical switching
  • Demultiplexing of OTDM channels
  • Wavelength conversion of WDM channels

Disadvantages of XPM[edit]

  • XPM leads to interchannel crosstalk in WDM systems
  • It can produce amplitude and timing jitter

See also[edit]

External links[edit]