Second harmonic generation microscopy: experiments and theory

Second harmonic generation (SHG) microscopy, involving the doubling of the frequency of light by a material, is a valuable characterization technique that is highly sensitive to local material symmetry at lengths scales close to the diffraction limit. The use of high-NA microscope objectives introduces an additional layer of complexity when performing quantitative analysis of SHG polarimetry data due to the appreciable effects that strong focusing has on the polarization of the probe beam. A systematic investigation of this problem is presented, producing analytical and numerical solutions of SHG polarimetry generated under high-NA lenses in a microscope setup. Modeling of a variety of standard samples, from single crystals to thin films, is performed and compared against experimental data.