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