Wavelength- and Polarization-Multiplexed Dielectric Metasurface for On-Demand Generation and Continuous Tuning of...

Despite progress in optical multiplexing, integrating discrete channel switching with continuous control of distinct optical fields in a single metasurface remains challenging. Here, we numerically demonstrate a dielectric metasurface that enables wavelength- and polarization-selective generation of focal spots and perfect vortex beams (PVBs), with their relative contributions continuously tuned via the incident ellipticity without reconfiguring the structure. This functionality is enabled by combining wavelength-selective Si nanopillars with Pancharatnam-Berry geometric-phase encoding, which decouples wavelength selectivity from phase control. Under circularly polarized illumination, focal spots and PVBs are selectively generated at both 532 nm and 632.8 nm. The generated PVBs exhibit a common ring radius with wavelength-dependent topological charges of l = +4 at 532 nm and l = -2 at 632.8 nm, and their modal purities reach 79.7% and 97.7%, respectively. Under horizontal linearly polarized light, both circular-polarization channels are simultaneously excited to produce a hybrid field composed of a focal spot and a PVB. As the ellipticity increases, the ratio of PVB to focal spot intensity rises continuously, in good agreement with the analytical modal. The flexibility of the proposed approach is further demonstrated by off-axis focusing, non-uniform phase PVB generation, and control of the PVB ring radius. This work provides a reconfiguration-free platform that combines wavelength- and polarization-selective switching with continuous control of relative modal contributions, offering potential applications in optical trapping and mode-division multiplexing.