Flexible Design of Polarization-Insensitive Metasurface Lens Based on the Equal-Phase Method

We introduce an equal-phase method to design the polarization-insensitive metasurface lens, composed of subwavelength nano-holes etched into a silver film. By calculating the intensity distribution under linearly, circularly, and elliptically polarized light illumination, we demonstrate that the designed metasurface lens can effectively focus incident light with different polarization states. Moreover, we confirm that this polarization-insensitive property of the designed lens maintains stable focus ability across the entire visible light bandwidth, exhibiting a broadband performance. It is important to note that the metasurface lens design based on the equal-phase method is not limited by specific nanostructure units and exhibits considerable flexibility. For some complex application conditions, we also explore the design of polarization-insensitive lenses capable of generating longitudinal and transverse dual focal spots. The metasurface lenses and the design method proposed in this paper may provide a reference for the development and application of polarization-independent components in integrated photonic devices.