SPM vs CPM vs FWM-Difference between SPM,CPM,FWM optical nonlinear refractive effects

This page compares SPM vs CPM vs FWM optical nonlinear refractive effects and mentions difference between SPM, CPM and FWM.

Nonlinear effects in optical fibers➤ occur due to following reasons:
➨change in the refractive index of the medium with optical intensity
➨inelastic scattering phenomenon

Nonlinear Refractive Index effects are divided into following:

Inelastic Scattering Effects are divided into following:
• SRS (Stimulated Raman-Scattering)
• SBS (Stimulated Brillouin-Scattering)

Optical effects-SPM CPM FWM

Following table compares SPM, CPM and FWM.

Characteristics SPM CPM FWM
Full form Self-Phase Modulation Cross-Phase Modulation Four-Wave Mixing
Bit rate Dependent Dependent Independent
Origin Nonlinear susceptibility χ(3) Nonlinear susceptibility χ(3) Nonlinear susceptibility χ(3)
Effects of χ(3) Phase shift due to pulse itself only Phase shift is alone due to co-propagating signals new waves are generated
Shape of broadening symmetrical May be a symmetrical -
Energy transfer between medium and optical pulse No No No
Channel Spacing No effect Increases on decreasing the spacing Increases on decreasing the spacing


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