Second harmonic generation of a vector light field with azimuthally varying state of polarization

Abstract

The second harmonic generation (SHG) of a vector light field with azimuthally variant states of polarization (SoP) including both locally linear polarization and hybrid polarization is experimentally and theoretically demonstrated. With nonlinear frequency conversion by using a Type-II BBO crystal, we can double the wavelength of 800 nm near-infrared light to generate 400 nm ultraviolet light. The spatial distribution and transmission of the second harmonic field with an ultrafast pulse pump with spatially variant SoP indicate the interesting topological transformation law. The experimental results of the topological transformation with a fundamental vector optical field with either the locally linear polarization or hybrid SoP (simultaneously possess the linear, elliptical and circular polarizations in the field cross-section) are in agreement with the theoretical predictions. These results may provide further manipulation of the vector optical field and find potential applications in the corresponding fields such as ultraviolet micromachining, micro-particle processing and quantum optics.