Multichannel Spatially Nonhomogeneous Focused Vector Vortex Beams for Quantum Experiments

The utilization of vector vortex beams (VVBs) in quantum experiments has recently become a topic of tremendous interest. However, achieving a focused, high‐resolution, transmission‐type, multichannel, and nonhomogeneously polarized VVB array remains a great challenge. Here, by introducing a degree of freedom on a high‐order Poincaré sphere in the form of latitude‐polarization control and locally tailoring the phase and transverse polarization distributions at the subwavelength scale, a single transmission‐type dielectric metalens design for producing a multichannel, spatially nonhomogeneous, focused VVB array is demonstrated. Three special kinds of lattices (triangle, square, and rhombus) are demonstrated, yielding independently controllable orbital angular momentum states and polarization states of a tightly focused field in each channel. Furthermore, by using only the proposed metalens and a polarizer, a mode‐demultiplexing system is realized with a mode crosstalk as low as −34.8 dB for all four channels. The results offer a robust technological foundation for exploiting spatial degrees of freedom of structured light in the miniaturization and integration of quantum photonics devices. By introducing a degree of freedom on high‐order Poincaré sphere in the form of latitude‐polarization control and locally tailoring the phase and transverse polarization distributions, a single transmission‐type dielectric metalens for producing multichannel spatially nonhomogeneous focused vector vortex beams is demonstrated. Furthermore, a mode‐demultiplexing system with a mode crosstalk as low as −34.8 dB is realized for quantum experiments.