Optical second harmonic generation microscopy under circularly polarized beam

Second harmonic generation (SHG) results from molecules being polarized by an external electric field, often provided by an intense laser beam. The polarizability depends on firstly the intrinsic structural properties of the substance and hence the second order nonlinear susceptibility, and secondly the intensity and polarization direction of the incident light. The polarization characteristics of the beam are therefore of interest. In this paper, we discuss some considerations in SHG microscopy when the incoming beam is circularly polarized, and present some supporting results as well as a question for future work.