Quasi-3-D beam-propagation method for modeling nonlinear wavelength conversion

The two-dimensional (2-D) iterative finite difference beam-propagation meth od (IFD-BPM) is modified to model the cylindrically symmetric three-dimensi onal (quasi-3-D) second-order nonlinear wavelength conversion in quasi-phas e-matched condition. The study shows that the difference between the 2-D an d 3-D schemes is small for the guided waves but large for the nonguided bea ms, The comparison with experimental results shows that the quasi-3-D IFD-B PM is closer to reality than the 2-D scheme. In addition, simulation using the quasi-3-D IFD-BPM reveals that plane-wave and Gaussian-beam assumptions are not sufficient for estimating the nonlinear conversion and beam propag ation in second-order nonlinear devices.