Second-harmonic generation from realistic film–substrate interfaces: The effects of strain

The optical second-harmonic generation from a thin crystalline film on a substrate is theoretically investigated for both s and p polarized incident light. The contributions of lattice misfit strain as well as of misfit dislocation strain to the second-order nonlinear optical susceptibility are described using a nonlinear photoelastic tensor and can be separated by a polarization analysis of the scattered light at the second harmonic frequency. For the s(ω)→s(2ω) and p(ω)→s(2ω) scattering geometries, the nonlinear optical signal will be determined by dislocation strain only, whereas for the s(ω)→p(2ω) and p(ω)→p(2ω) geometries both lattice misfit strain and misfit dislocation strain will contribute.