Subwavelength focusing of azimuthally polarized beams with vortical phase in dielectrics by using an ultra-thin lens

TL;DR

This paper presents a planar, ultrathin binary lens capable of focusing azimuthally polarized beams with vortical phase to subwavelength spots, maintaining focus beyond diffraction limits through dielectric interfaces, enabling advanced optical applications.

Contribution

The study introduces a novel ultrathin binary lens design that achieves subwavelength focusing of azimuthally polarized vortex beams and maintains focus across dielectric interfaces, surpassing traditional limitations.

Findings

Achieves subwavelength focusing with azimuthally polarized vortex beams.

Maintains focused spot beyond Rayleigh diffraction limit through dielectric interfaces.

Enhances applications in super-resolution imaging and wafer inspection.

Abstract

We demonstrate that a planar and ultrathin binary lens can focus an azimuthally polarized beam with vortical phase (APV) to a subwavelength spot of transverse polarization. The results elaborates that, in the multi-layer medium, this focused spot, which is beyond the Rayleigh diffraction limitation, can be well maintained for several wavelengths after travelling through the dielectric interfaces, which is not attainable by using other vector beams (i.e., radially, linearly and circularly polarized beams) as the illuminating light. This compact optical system can be valuable in data writing and defect identification of wafer or silicon chips, owing to the enhanced polarized focusing through interfaces. It also enables to be highly integrated with traditional microscopy for the far-field super-resolution imaging, surface scanning and detection, and subwavelength focusing, owing to the enhanced focusing performance (reduced width and extended length) as well as the planarized configuration of the ultrathin lens.