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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

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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 nonlinear medium. This technique is applied to fiber-optic communications. If both beams have the same wavelength, then this type of cross-phase modulation is degenerate.[1]

XPM is among the most commonly used techniques for quantum nondemolition measurements.

Other advantageous applications of XPM include:

Disadvantages of XPM

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XPM in DWDM applications

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In dense wavelength-division multiplexing (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 effect of XPM.

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

See also

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References

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  1. ^ a b Petrov, Nikolay V.; Sergei S. Nalegaev; Andrei V. Belashov; Igor A. Shevkunov; Sergei E. Putilin; Yu-Chih Lin; Chau-Jern Cheng (2018). "Time-resolved inline digital holography for the study of noncollinear degenerate phase modulation". Optics Letters. 43 (15): 3481. Bibcode:2018OptL...43.3481P. doi:10.1364/OL.43.003481. PMID 30067690. S2CID 51893588.
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