How to use a tensor with non-zero non-diagnal coefficients as the nonlinear susceptbility?

[wangzhenhao1994]

In the "Feature/Material/Nonlinearity" part of the online doc, it says "Meep supports instantaneous, isotropic Pockels and Kerr nonlinearities". Is it possible that I use the rank-3 tensor (second order nonlinear susceptbility) of a anisotropic crystal which has non-diagnal coefficients?

[wangzhenhao1994]

I realize something but not very sure:"anisotropic electric permittivity ε and magnetic permeability μ, along with dispersive ε(ω) and μ(ω) including loss/gain". So I can just use εE = ε₀E + XeE to represent the aniostropic property of the material ?