NonLinearPolarization¶

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Appearance:	multiple

Defines a time-harmonic polarization $\TField{p}^{(n)}$ that serves as the source of $n$ -th order nonlinear phenomena. For example, the polarization source $\TField{p}^{(2)}$ corresponds to second-order nonlinear optical process, and can be expressed as:

$\begin{alignat*}{1} \TField{p}_i^{(2)} & = \epsilon_0 \sum_{j,k} \chi_{ijk}\TField{E}_{j}^{1}\TField{E}_{k}^{2} \end{alignat*}$

For example, one defines the nonlinear polarization in the sources.jcm as:

SourceBag {
  Source {
    DomainId = 4  # Domain ID where the polarization source is located
    ElectricCurrentDensity {
      NonLinearPolarization {
        ElectricField {
          FieldBagPath = "../fundamental/project_results/fieldbag.jcm"  # path to the fieldbag.jcm generated in linear simulation
          FieldId = 1   # Optional: Field ID if multiple RHSs were used in linear simulation
        }
        Chi = [
          123: 740.0e-12,
          132: 740.0e-12,
          231: 740.0e-12,
          213: 740.0e-12,
          312: 740.0e-12,
          321: 740.0e-12
        ]
      }
    }
  }
}