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

Abstract

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.

Optical imaging of strain in two-dimensional crystals

“…The second harmonic response in these works is typically described by a phenomenological modification of the nonlinear susceptibility of the unstrained material [31][32][33][34][35]. In a more thorough theoretical investigation, Lyubchanskii et al demonstrated that strain and nonlinear susceptibility are connected via a photoelastic tensor [36,37].…”

Direct observation of controlled strain-induced second harmonic generation in a Co0.25Pd0.75 thin film on a Pb(ZrTi)O3 substrate

“…17 The significantly smaller SHG signals for s in → S out and p in → S out geometries can be explained by the small values of yyy ͑2,0͒ and yxx ͑2,0͒ , together with a contribution from the misfit strain between the Pd/ Co 0.25 Pd 0.75 / Pd trilayer and the substrate. 2 Here, at the coercivity voltage U c = ± 3 V, the contribution to the SHG signal from the electric polarization P equals zero. 12 As a result, only the nonzero components of the second-order NOS and of the NPE tensors contribute to the SHG signal for this situation.…”

“…1 Strain-induced SHG in bulk materials and thin films was studied theoretically 2,3 and experimentally for various systems such as Ba 0.48 Sr 0.52 TiO 3 on a MgO͑001͒ substrate, 4 BaTiO 3 and Ba x Sr 1−x TiO 3 thin films and BaTiO 3 / SrTiO 3 superlattices, 5,6 semiconductor interfaces 7 and silicon wafers, 8,9 group III-nitride films, and thin Ag films on Si͑111͒ substrates. 10,11 In most of these experimental papers strain was irreversibly induced by lattice mismatch between the film and the substrate, 4,[8][9][10][11] whereas in Ref.…”

Nonlinear Optical Diffraction by Standing Acoustic Waves in a GaAs Film

“…The effect of acoustically-induced optical SHG was also observed in GaAs films in the infrared region where this material is transparent [19]. Later, strain-induced three-photon effects such as optical SHG in strained crystals and hyper-Rayleigh light scattering by dislocation deformation were theoretically investigated [20], as well as SHG due to misfit strain and misfit dislocations at filmsubstrate interfaces [21]. Similarly, experimental observations of strain-induced SHG were reported in silicon wafers [22] and the influence of strain on SHG in Co 0.25 Pd 0.75 films on a PZT substrate [23], in bismuth-substituted iron garnet films [24], as well as in bulk silicon [25,26] were discussed.…”