Three-dimensional nonlinear Stokes–Mueller polarimetry

The formalism is developed for a tree-dimensional ($3D$) nonlinear Stokes-Mueller polarimetry. The expressions are derived for the generalized $3D$ linear and nonlinear Stokes vectors, and the corresponding nonlinear Mueller matrix. The coherency-like Hermitian square matrix $X$ of susceptibilities is introduced, which is derived from the nonlinear Mueller matrix. The $X$-matrix is characterized by the index of depolarization. Several decompositions of the $X$-matrix are introduced. The $3D$ nonlinear Stokes-Mueller polarimetry formalism can be applied for three and higher wave mixing processes. The $3D$ polarimetric measurements can be used for structural investigations of materials, including heterogeneous biological structures. The $3D$ polarimetry is applicable for nonlinear microscopy with high numerical aperture objectives.