Mapping the nonlinear optical susceptibility by noncollinear second-harmonic generation

Conical second harmonic generation in KDP crystal assisted by optical elastic scattering

We observed the generation of phase-matching conical second harmonic generation (SHG) inside KDP crystal under anomalous dispersion condition, which is attributed to complete phase-matching assisted by fundamental wave (FW) and scattering wave. The double-ring pattern of the conical SHG implies that elastic scattering can stimulate two different polarization states of scattering wave. Furthermore, SH ring of KDP displays inhomogeneous intensity around the ring, which has relevance to effective nonlinear coefficient, and it can be used to investigate crystal symmetry.

Evidence of multipolar response of Bacteriorhodopsin by noncollinear second harmonic generation

Noncollinear second harmonic generation from a Bacteriorhodopsin (BR) oriented multilayer film was systematically investigated by varying the polarization state of both fundamental beams. Both experimental results and theoretical simulations, show that the resulting polarization mapping is an useful tool to put in evidence the optical chirality of the investigated film as well as the corresponding multipolar contributions to the nonlinear.

Bound and free waves in non-collinear second harmonic generation

We analyze the relationship between the bound and the free waves in the noncollinear SHG scheme, along with the vectorial conservation law for the different components arising when there are two pump beams impinging on the sample with two different incidence angles. The generated power is systematically investigated, by varying the polarization state of both fundamental beams, while absorption is included via the Herman and Hayden correction terms. The theoretical simulations, obtained for samples which are some coherence length thick show that the resulting polarization mapping is an useful tool to put in evidence the interference between bound and free waves, as well as the effect of absorption on the interference pattern.