Breaking the Diffraction Limit with Radially Polarized Light Based on Dielectric Metalenses

Dielectric metalenses with high efficiency and compact size have been widely investigated recently, but still suffer from Abbe diffraction limit. Herein, with linear polarization incidence, a dielectric metalens is demonstrated to efficiently generate and focus radially polarized light simultaneously. Two novel methods are proposed to achieve super-resolution. First, a circular high-pass aperture is utilized to enhance the longitudinal field component in the vicinity of focus with the focal spot size of 0.138 lambda(2), much smaller than the theoretical limit of 0.212 lambda(2). The key parameters that impact the focusing size are explored in detail, such as radius of the circular aperture and numerical aperture of the metalens. Second, an extra phase distribution is added on the metalens to filter the transversely polarized component, which leads to a focal spot size of 0.144 lambda(2). The approach provides a wide platform for sub-resolution focusing and imaging, which offers the capability of subdiffraction techniques for microscopy systems and information processing with extensive channels.