Cross-phase modulation
Encyclopedia
Cross-phase modulation is a nonlinear optical effect where one wavelength of light can affect the phase of another wavelength of light through the optical Kerr effect
.
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.
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.
Kerr effect
The Kerr effect, also called the quadratic electro-optic effect , is a change in the refractive index of a material in response to an applied electric field. The Kerr effect is distinct from the Pockels effect in that the induced index change is directly proportional to the square of the electric...
.
Applications of XPM
Cross-phase modulation can be used as a technique for adding information to a lightLight
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
stream by modifying the phase
Phase (waves)
Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.-Formula:The phase of an oscillation or wave refers to a sinusoidal function such as the following:...
of a coherent
Coherence (physics)
In physics, coherence is a property of waves that enables stationary interference. More generally, coherence describes all properties of the correlation between physical quantities of a wave....
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
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.
See also
- Self-phase modulationSelf-phase modulationSelf-phase modulation is a nonlinear optical effect of light-matter interaction.An ultrashort pulse of light, when travelling in a medium, will induce a varying refractive index of the medium due to the optical Kerr effect...
— SPM - Four wave mixing — FWM
- Stimulated Raman scatteringRaman scatteringRaman scattering or the Raman effect is the inelastic scattering of a photon. It was discovered by Sir Chandrasekhara Venkata Raman and Kariamanickam Srinivasa Krishnan in liquids, and by Grigory Landsberg and Leonid Mandelstam in crystals....
— SRS