The Inverse Scattering of Second-Order Nonlinear Media Based on Distorted Born Iterative Method

Nonlinear media are the building blocks for nonlinear optical devices. The parameter retrieval of nonlinear media is an important problem for nonlinear optics. However, the maturity and accuracy of nonlinear media retrieval methods lag behind that of ordinary linear media retrieval methods because it is difficult to analytically solve the Maxwell equations containing nonlinear media. Various approximations and simplifications have to be made in order to derive the analytical formulas for nonlinear parameter retrievals. Since the material’s electromagnetic (EM) parameter retrieval problem belongs to the EM inverse scattering problem, the accuracy of nonlinear media parameter retrievals can be improved if EM inverse scattering techniques, which are full-wave numerical methods, can be employed. Conventionally, EM inverse scattering methods work for linear media. In this communication, we generalize the distorted Born iterative method (DBIM), which is a popular EM inverse scattering method for linear media, to the second-order nonlinear media case. The numerical tests show that the nonlinear parameter distribution of a 1-D problem can be determined with the generalized DBIM.