non linear optic

Try this one:
https://www.edaboard.com/viewtopic.php?t=61112

linear or non linear optic depend on operating optical power that comes into the fiber
when we're working on linear optic, we're operating low optical power.
linear optic is limited by a power level threshold,
if we increase the optical power we will work on non linear optic.
There are two thresholds usually used in optic system,
Ramman Scattering and Brillouin Scattering. These two thresholds determined by fiber optic's diameter,light source's bandwidth, light's wavelength

Nonlinear optics is the part of Electromagnetic theory which checks Maxwell's equations for waves in the optical range of the frequency spectrum (10e12-10e16Hz) in special medium that are nonlinear in response. The specific materials have the special characteristic that when trying to solve maxwell's equations for them (taking in to account their material properties) the evolution of the waves depends on their initial amplitude. Most of the nonlinear phenomena are due to the "special properties" of the Polarization field vector of the material. Fundamentally, this goes back to the response of the atoms of the specific material to electromagnetic waves and mathematically it manifests it self in a dependence of the refractive index of the material on the amplitude of the electric field wave.

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