S

 

The second order susceptibility χ⁽²⁾ is related to nonlinear effects such as linear electro-optic or Pockels effect (where index changes with applied dc electric field), and second harmonic generation (where the light output wavelength is halved relative to the input). It is generally non-zero for media without molecular symmetry and, as silica is composed of symmetric O-Si-O molecules, optical fibers do not tend to exhibit nonlinear effects related to second order susceptibility.

Related Terms: Nonlinear Effects, Nonlinear Index, Nonlinear Parameter