Generation and manipulation of vortex beams in optical superlattice

Light beams carrying orbital angular momentum (OAM) are called vortex beams. Due to the novel phase distribution and the physical properties, such beams are widely used in optical micro-manipulation, super-resolution imaging, high-capacity communication, and quantum information technologies. As different applications require light sources with different wavelengths, nonlinear frequency conversions in optical superlattice through quasi-phase-matching provide a promising way to extend the wavelength of vortex beams. For the interaction between vortex lights and nonlinear medium, the conservation of energy, linear momentum as well as OAM should be concerned. Herein, recent progress on nonlinear generation and manipulation of optical vortices in optical superlattice is reviewed. Through nonlinear frequency conversion including second and third harmonic generation, sum frequency generation, and frequency down conversion processes, the working wavelength of the vortex beam can be efficiently extended from blue-violet to mid-infrared band. The transfer of OAM in the frequency conversion process can be flexibly controlled by precisely designing the optical superlattice. Designing nonlinear photonic crystals exploiting nonlinear holography, one can modulate the wavefront, phase, and amplitude of the light field during the frequency conversion process, thus the nonlinear generation and manipulation of vortex beam can be realized. With the development of the superlattice fabrication technology, the manipulating dimension of light field has been expanded from two-dimension to three-dimension. Investigations on the generation and manipulation of vortex beams in optical superlattice can deepen the understanding of OAM as well as promote the progress of the related applied research. © 2020, Editorial Board of Journal of Harbin Institute of Technology. All right reserved.